Fact and Fancy

Citation preview

ISAAC ASIMOV Author of ‘'The Intelligent Man’s Guide to Science"

Man — the planets — the Universe — seventeen speculations on science and its possibilities With an 8-page picture section

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The Worlds ViScience GENERAL

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"p> HOW MANY STARS CAN YOU SEE?

WILL THERE BE ANOTHER ICE AGE? »». maybe not, unless all the factories shut down!

~

(“No Moré Ice Ages?”)

3

> WHAT LIES BEYOND THE PLANETS?

. +. just possibly, a lot of ice!

an

(“Steppingstones to the Stars”)

-—

p> WHEN CAN YOU ESCAPE THE REACH OF GRAVITY? ».» you can’t—ever!

(“Catching Up with Newton”)

Ri i es i

These questions give a hint of the scope and excitement of Dr. Asimov’s new book—a treasury of startling ideas and sound scientific information, as sure to entertain as it is to enlarge the reader’s horizons.

‘Gives

a new

and

refreshing

°

—

sense of the

Jniverse’’ —Pacific Discovery

ISAAC

ASIMOV

Dr. Asimov,

author

of more

than

fifty science

and

science-fiction books, was born in Russia in 1920 and emigrated to the United States with his parents in 1923. His parents’ newspaper-magazine store in Brooklyn, plus “every public library within ten miles” provided him with reading matter and sparked his interest in both the factual and fanciful aspects of science. He began to write science-fiction while studying at Columbia University, where he majored in chemistry and eventually received a Ph.D. He is married, has two children, and lives in West Newton, Massachusetts;

Associate

Professor

of Biochemistry

at Boston

he is

Uni-

versity, although he now devotes all his time to writing,

Among Dr. Asimov’s many and varied books are: The Intelligent Man’s Guide to Science; Life and Energy; |, Robot; and The Caves of Steel.

aie e TO eS oe ee toes

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THEBeworLos oF science |3—_* i

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PYRA MID PUBLICA TIO NS .

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‘

eS eo S Se E

FACT AND

FANCY

A WORLDS

OF

‘

SCIENCE

BOOK—published

by arrangement

& Company,

Inc.

with

Doubleday

.

PRINTING HISTORY—Doubleday & Company edition published April 1962 First

printing

.°.

.

Januar

1962

Second printing . » ». March 1962 Worlds of Science edition published September

Library of Congress

Catalog Card Number 62-7598

Copyright © 1962 by Isaac Asimov mete Copyright 8 1958 by Street & Smith Publications, Inc. Copyright © 1958, 1959, 1960, 1961 by Mercury Press, Inc.

1963

bild All Rights Reserve:

|

Printed in the United States of America

WORLDS OF SCIENCE books are published by Pyramid Publications, Ince, 444 Madison Avenue, New York 22, New York, U.S.A.

Ss. = -”

ea jl

To the fine gentlemen responsible:

Joseph W. Ferman

Robert P. Mills

Introduction

|

.

he dullness of fact is the mother of fiction. How many lies ‘

riginate out of no desire to escape punishment, amass undue

redit, or gain an end, but simply to make a good story. And

| story, endlessly repeated, grows by accretion of false detail, — ‘0 that the fish one almost catches

becomes larger, the retort

to the boss more biting, the fright more frightful, and the harrow escape incredibly hairlike. . _ Fortunate the man who, by profession, can lie freely and - es call it a novel. If he lies skillfully and evocatively enough, revealing, as he does so, a piece of mankind to itself, he may even attain immortality and the eternal gratitude of mankind in place of the impatient sneer that is the usual reward of the liar, _ And contrariwise, sad the lot of the man who, in his writ-

ing, finds himself in a field so dedicated to fact, however dull, that the least deviation in a moment of carelessness is viewed with serious alarm. __ To what field can I be referring but that of Science, the cold and rigid apostle of “truth-as-we-now-see-it.” The facts,

gentlemen, and nothing but the facts, for careful eyes are narrowly watching. _ I call you, then, to witness my own peculiarly exacerbated difficulty as a science writer, for I began my writing career in. fiction and in twenty years wrote well over a hundred short stories and novelettes plus a dozen or more novels. My instinct for embroidery is so well-developed now, one might say hypertrophied, that it quivers in agony at the first distant clumping that heralds the approach of a dull fact. Surely there must be some middle ground between the four-squareness of the fact, the solidity of its flat feet, the thud of its stone sandals, and the iridescent gauziness of a complete lie flitting its way through-the ether.

Iam told, and I know, that Science is fascinating and adRass

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in

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Fact and Fancy

venturesome; that it bears the burning mark of the greatest of Be)

~~

all frontiers, that of the human mind facing the darkly infinite

. a

~ sea of the unknown that hems it in.

To me there is no pleasure in the writing of science f 19 cannot make the effort of capturing some of the gauze and © iridescence that belong to the truths snatched out of the chaos ~ of ignorance, far more than they can ever belong to some ~ < uny lie. ‘ Een think of no better word for that gauze of truth than ©

“fancy.” a The distance of the moon from the earth and from the suns” the sizes and motions of the three bodies are facts. To deduce” therefrom the vision of an eclipse of the sun by the earth, as ~ seen from the moon, is no lie, even though no such sight has ©

et been seen by the corporeal eye of a living man. The very

©

fact that it is basic truth, not yet fully revealed, makes it far™

more fascinating than any lie could be. It is fancy. ‘ The sun has a family of nine known major planets. That is~ fact. A tenth planet may exist, for all we know, and if so, cer-©

tain facts may be deduced from what we already know about ~ the rest of the system. That is fancy.

4

There are—possibly—icy asteroids circling in space, that the whole solar system we

the sun, so far out” { know today shrinks©

almost to a dot in comparison. It is possible that matter comes into existence at a terribly slow rate and disappears again just as slowly—well, perhaps. Man has seen distant stars: explode and grow incredibly bright. He has never seen a neighboring star do so and grow in brightness to rival our own sun for a few weeks. The vision of that and an infinity of other wonders belong to fancy. The art of the lie can touch

nothing so grand.

~ ©

© ~ © ©

q

And so I resolve my dilemma. The hospitable pages of the ~ Magazine of Fantasy and Science Fiction are thrown open — each month to me, and there, under the kindly egis of editor Robert P. Mills* and free of all limitations and censorship, I 3 fit out my facts, as best as ever I can, with the ga © gauzy wings Winesa

of fancy, and send them flying. | The following collection of articles are (with one exception) ‘ from the pages of that magazine, and if there is even half the _ fun in the reading that there was in the writing, I will be delighted. a * Now

(1963) a full-time, but still kind, literary

zine’s editorship has passed to Avram

acent:

Davidse,

ian

7

ae

pally hospitable to the articles succeeding the ones in this book.

m4 titecthe bec vst tg Setyt tow wets 'ubgyir! ae hen Ale: 5

arto

2

1 Life’s Bottleneck Villains on a cosmic scale are where you fi , and the imagination has found some majestic ones including exploding suns and invading Martians. Re in recent years, has found some actual villains that uld have seemed most imaginary not too long ago, as,for: stance, nuclear bombs and melting icecaps.

But there are always a few more, if you look long enou —like sanitary plumbing and modern sewage dispos ‘Well, let me explain.

_ To begin with, let’s consider the ocean, the mother of all Epic gs living. Out of its substance, some billions of years ago ‘“ formed, utilizing for the purpose the various types

atoms found in the ocean, though it had to juggle the px portions a bit.

5

For instance, the ocean is mainly water, and so is living :

tissue. The ocean is 97 per cent water by weight, while living things in the ocean are about 80 per cent water, generally spe

4

ric, this is not quite a fair comparison. The water molecule is made up of two hydrogen atoms and an oxygen atom. In the ocean,

water itself is the only substance, t

speak of, which contains these atoms. In living matter, how. ver, hydrogen and oxygen are contained in many of the onstituent molecules other than water; and all this

hydrogen

nd oxygen came from water originally. This “hydrogen-andxygen-elsewhere” should be counted with water, therefore, _ To get a more proper panorama, let’s consider the percentage by weight of each constituent type of atom. We can this for the ocean, and for the copepod, a tiny crustace is one of the more common forms of the ocean’s swarm The eas are 2 ae in Zable 1,

. Fact and Fancy

Poke

_

f

q

4%

Thecolumn headed “Concentration Factor” in that table is

_ the most important part of it. It represents the ratio of the percentage of a particular substance in living tissue to’ the

ercentage of the same substance in the environment. TABLE Per Cent a

Composition . of Ocean

ogen erything else

1 ’ Per Cent

Composition of Copepod

85.89 10.82 3.29

79.99 10.21 — 9.80

4

Concentration Factor ~

- 0.93 0.94 3.35

For instance, oxygen and hydrogen are found in smaller ercentage in tissue than in ocean so the concentration factor— or each is less than

1, as shown

in the table. To convert

00 pounds of ocean (containing 96.71 pounds of hydrogen — and oxygen) into 100 pounds of copepod (containing~90.20° _ pounds of hydrogen and oxygen) 6.51 pounds of hydrogen __ and oxygen must be gotten rid of. ;

__ Whenever the concentration factor for any substance is less / _ than 1, it means that that particular substance, potentially at Teast, can never be a limiting factor in the multiplication of~ iving things. Life’s problem will always be to get rid: of it, ather than to collect it. ; I me _ The situation is the reverse

as far as “everything else” is

_ concerned. Here 100 pounds of copepod contains 9.80 pounds — _- of “everything else” while 100 pounds of ocean—out of which e copepod is formed—contains only 3.29 pounds. It takes — 5 pounds of ocean to contain the 9.80 pounds of “every-_ thing else.” z a

___A concentration factor greater than 1 sets up the possibility. ” -of a bottleneck. Ideally, life could multiply in the ocean till the entire ocean had been converted into living tissue. After —

all, what is there to stop the endless and unlimited multiplication of life? ____ Well, suppose you begin with 335 pounds of ocean. By the — _ time copepods have multiplied to a total weight of 10 pounds, they have incorporated all the “everything else” i

supply of ocean into their own bodies. There is still 235 —

ids of ocean left, but it ispure water and cannot be cond into copepod. =. lat ne Meee

Dia iain

>

a, ee Life’s Bottleneck ©

13

‘The greater the concentration factor, the more quickly that—

imit would have been reached and the smaller the fraction —

total environment that can be converted into living

_ Of course, I have deliberately simplified the matter,a | begin with, in order to make the point. Actually, the “ever re

else” is a conglomerate of a dozen or so elements, each hich is essential to life, and none of which can be dis-3

Each ead

element is

Dcean; each is present in

present in different amounts in the ,

ferent amounts in living tissue,

Rach, therefore, has its own concentration factor. As soon as y one of them is completely used up, the possibility of tthe urther expansion of life, generally, halts. One form of life can ow at the expense of another, but the total quantity of oe asm can increase no further.

isBthe one first used up and is, het

life’s hottinede

ry

_ Let's therefore compare the ocean and the copepod in ines“4 :—ai es the hydrogen and oxygen and just considering verything else.” This is done in Table 2. § fy can see that concentration factors do indeed vary —

widely from element to element. Only four elements have

actors that are really extreme; that is, over a thousand. Of — hese four, the values for carbon and nitrogen are not really

as extreme as they seem, however, since the ocean is not dnl

only source of these elements. There is, for instance, some car= bon dioxide in the air, and all of that is available to ocean lito

TABLE 2 Per Cent

a

Per Cent

Composition Composition of Ocean _ of Copepod —_—_—=—=_—_—_—_——

Carbon

Nitrogen

odi Potassium Calci

esium

6.10

2.04

1.05

1.09 0.042

0.54 0.29

0.00008

hlorine

‘hosphorus

—————

0.0031

~

1.52

0.097

0.00001T - = 0.0024

Ae

oe

0.14

0.13: ~ 0.04

20.08

a

Concentration — Factor ES oS

i

’

iGron’ .

0.007

0.0004

Silicon

_ Bromine v Iodine

_

0.0072 0.000005

=

0.007

~w-. 0.000002 _

_

rae

@

@ Fact and Fancy

14

3500. am 17. a

0.12 * 40.

0.0009 0.0002

_ (And the supply of atmospheric carbon dioxide is increasing

idthese days as we burn coal and oil.)

There

|

“4

is also a vast quantity of nitrogen in the air; much ~

- more than there is in the ocean. This is available to ocean —

_ life, too, at least-indirectly, through the activity of. nitrogen-~~ _ fixing bacteria. These convert gaseous. nitrogen, which is it- — self unusable to higher forms of life, into nitrates, which are ~

usable. For

a these “reasons, neither carbon nor nitrogen can ever —

_ be considered bottlenecks against the additional formation of ~ __ total protoplasm. There is only a finite quantity of both, but ~ _ long before life feels the pinch in either carbon or nitrogen, there is the shortage of iron and phosphorus to be continued, And here phosphorus is four times as critical as iron. The — - copepod, of course, is only one type of life, but in general this~ _ pattern carries through. Phosphorus has the highest concen- ~~ tration factor; it is the first element to be used up. Life can ©

multiply until all the phosphorus is gone and then there is © an inexorable halt which nothing can prevent. : = Even that much is only possible under favorable energy — conditions. For it takes energy to concentrate the phosphorus —

and iron of the ocean to the levels required by living tissue. © _ For that matter, it takes energy to expel enough of the chlo- © _ rine, sodium, magnesium, and bromine to bring their concen- ~

trations down to levels tolerated by living tissue. It also takes—

energy to convert the simple low-energy compounds of the ~ ocean (even after appropriate concentration or thinning out) ~ _ into the complicated high-energy compounds characteristic — of living tissue.

.

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et

No More

‘I

Ice Ages

@ (29° 2

Of course, why theorize as to how the ocean may ‘tical ee ~arbon dioxide, how slowly the atmospheric carbon dioxide

ay be building up, how quickly the Earth may be turning

=

nto an iceless tropical world. Why not actually measure the ‘icecaps of the world and see if they are disappearing or not. —

And if they are se! ae how quickly? This, in fact, ‘was one of the prime objects of research for the Geophysical ‘Year and one of the most important reasons for all ne ‘scientists setting up housekeeping on the Antarctic icecap. _ _ We might also measure the actual over-all temperature of “the Earth and see if it is going up. If all the combusted carbon dioxide stays in the atmosphere, while dissolving in the Oceans at only a negligible rate, then the over-all tempera“ture ought to go up 1.1° C. per century. — According to Gilbert N. Plass of Johns Hopkins, such emperature measurements as are available indicate that just

this rate of temperature increase has indeed been going on > since 1900. Of course, temperature measurements during the— first half of the twentieth century are not reliable outside the more industrialized countries, so maybe this apparent — increase matches the theoretical only through a coincidence| arising from insufficient data. _ However, if this is more

than

coincidence;

4, if Earth is

‘really warming up at that rate, then wave good-by to the ©

icecaps. And if you live at the seashore, your not too distant _

descendants may well have to visit the old homestead with ©

-a skin-diver’s outtfit.

ot +

Earth has survived a similar fate three times in the last©

300,000 years, this current rise being the fourth. These — periods of rise make up what are called the “interglacial—

epochs.” Earth has also survived four periods of tempera- —

‘ture drop in this same period of time, each of which initiated_

a “glacial epoch” or, as it is more commonly known, an “ice — age.” It might seem that there is some physical phenomenon —

which brings on this coming and going of the ice, and one—

“would expect that same phenomenon to continue and to keep _

the

oscillation of ice and no-ice going for the immediate fu-'

‘ture (by which I mean the next few million years).

a

3 Yet prior to 300,000 years ago (for at least 200,000,000 —

years prior, in fact) there were no Ice Ages. For all that long period (or more) Earth was reasonably ice-free. Naturally, — the question arises: what happened 300,000 years agoP _ One explanation is that Earth undergoes a temperature os-

_cillation of a very slow and majestic type which didn’t make | w

on

S

®

ve

Fact and Fancy

-itselfvisible in the form of ice till 300,000 years ago. For ~~

instance, a Serbian physicist named Milutin Milankovich in i the 1920s suggested that because of oscillations in Earth’s —

. orbit and the tilt of its axis, the planet picks up a bit more

|

heat from the Sun at some times than at others. His pro-

posed temperature cycle lasted 40,000 years, so that there - is a kind of 20,000-year long “Great Summer” and a 20,000b year long “Great Winter.” The temperature differences-in- ~~ ‘a

,: _ volved are not really very great but, as I stated earlier a J drop.of less than 4°-C. in -Earth’s present temperature would. a}

__ = : be enough to kick off an Ice Age. Milankovich-oscillation can be made to explain the iThis

—

recent advances and retreats of the glaciers, but what about the situation B.I.A. (Before the Ice Ages)? ~

a ~ Well; what if prior to 300,000 years ago, Earth’s over-all ; _ temperature were sufficiently high so that even the Great ~ - Winter dip was not enough to bring on the ice? You can — see that, if you consider the annual temperature oscillation between ordinary summer and winter. In New York this os- 4

; cillation crosses the freezing point of water, so there is rain

__ in the summer but snow in the winter. In Miami the aver_ age temperature is higher and the oscillation does not dip low enough to bring snow in the winter. On a planetary Ei scale, what if Earth’s climate switched from iceless Miami ~~ "i to periodically icy New York? . 7 _ This possibility has been checked by isotope analysis, ~ (These days, if a scientist can’t get an answer by isotope — analysis, he ain’t hep.) There are three stable oxygen iso_

topes: oxygen-16, which makes up 99.76 per cent of all the

oxygen atoms; oxygen-18

(0.20 per cent)

and oxygen-17

(0.04 per cent). They all behave almost alike, so alike that ~ ordinarily no difference can be detected. However, oxygen-18

is 12% per cent heavier than oxygen-16 and correspondingly slower in its reactions. For instance, when water evaporates, ..

_ water molecules containing oxygen-16 get into the air a bit _ -more easily than those containing oxygen-18, and if evapora_ tion continues over a long interval the water that is left contains noticeably more oxygen-18 than it had originally. This applies to the oceans, which are constantly evaporat-

‘a ing, so-that sea water

_

should

(and does) have

; © — 3

a bit more

Oxygen-18, in proportion to oxygen-16, than does fresh wa- — ter, which is made up of the evaporated portion of the ~

oceans. Furthermore, this effect is increased as the tempera,. _ ture goes up. For each 1° C, rise in the temperature of the Reni 4 ~ ;

-

r

sis

ee

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No More Ice ‘Aci

the ratio of oxygen-18

to oxygen-16

31 =

goes up 0.084

_ Now then, fossil sea shells are made up largely of calcium Re: carbonate.

The

calcium

carbonate

contains

oxygen

a oms-

‘which were derived from the ocean water. The oxygen-18/te xygen-16 ratio in those shells must therefore reflect the ratio in the water from which they derived the oxygen and that, in turn, should give a measure of the ocean tempera-_

u es of ages long past.

_

Such measurements were first made in the laboratories of

Harold C. Urey at the University of Chicago and proved a very tricky job. On the basis of such measurements, however, it turns out that during the Mesozoic Age of old, When inosaurs were bold, the ocean temperatures were as high |4 as 21° C. (70° F.). Ss | This bespeaks a planetary temperature too high to allow ‘an Ice Age, even

at the bottom

of the Milankovich cycle. ‘|

_ But then, beginning 80,000,000 years ago, when re ‘temperatures were at the 21° peak, the temperatures started dropping and have continued to do so ever since. _ According to Cesare Emiliani (who carried temperature “Measurements into the recent past, geologically speaking) — ‘the explanation for this is that, after a long period of land_ area fairly free of mountains and oceans fairly free of abyss, ; “so that many shallow seas covered much of what is now land, a geological revolution occurred. The ocean bottoms arted sinking and mountain ranges started rising. | _ With land going up and ocean bottoms down, new land~ was exposed very gradually. Land stores less heat than docsf ‘water, radiating more away at night, so that the Earth’s “over-all temperature gradually dropped. Also, new hat ‘Meant new rocks exposed to carbon dioxide weathering,

hich meant a fall in the carbon dioxide of the atmosphere,—

‘a decrease of the “greenhouse effect,” and again,a a fallin j

temperature. . _ Quite possibly it was this fall in temperature that killedf

‘off the dinosaurs.

?

? By a million years ago, the steady drop of ocean tempera>/

ares had brought it down to 2° C. (35%° F.) and by 300,- — 100 years ago, Earth’s temperature was low enough to allow . the Ice Ages to appear at the bottom

of the Milpukoviea

ycles.

A iether: more startling debtkiation of the beginnin Ice Ages a been. vanced eeMaurice she=

a, oe:

uy “

ig it uA

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= ACLS

.

hte ¥

©

Fact and Fancy

xi

William Donn, working at Columbia. They blame it specifi- Re callyon the Arctic Ocean. The North Pole is located in a small, nearly landlocked _ bs a

arm-of the ocean, which is small enough and landlocked=—

enough to make possible an unusual state of affairs,

_. Thus*the suggestion is that when the Arctic Ocean is free 3

_ of ice, it acts as a reservoir of evaporating water that feeds snowstorms in the winter. If the Arctic Ocean were large~ “and open, most of-these snow storms would fall upon the _

Open. sea and there melt. As it is, the snow falls upon the ~ “surrounding land areas of Canada and Siberia, and. because

of the lower heat content of land areas, it does not melt but f remains during the winter. In fact, it accumulates from win=ter to winter, with the summer never quite melting-all the ia

ice

produced

by the preceding

winter.

and creep southward. Once

The

glaciers form

.

4

:

this happens, a considerable fraction of the Earth is

- covered with ice, which reflects more of the Sun’s radiation — __ than does either land or water. Furthermore, the Earth asa

»

_ whole is cloudier and stormier during an Ice Age than other- ~

2 wise, and the excess clouds also reflect more of the Sun’s ra_ diation. Altogether, about 7 per cent of the Sun’s radiation, __that would ordinarily reach Earth, is reflected during an Ice _ Age. The Earth’s temperature drops and the Arctic Ocean,

~ —

~ ~~

_ which (according to Ewing and Donn) remained open dur- —

_ ing the height of glacier activity, finally freezes over. (Even © despite the lowering temperature, it does this only because ~ “itisso small and landlocked.)

=

Once the Arctic freezes over, the amount of evaporation a from it is drastically decreased, the snowstorms over Canada ~ ‘and Siberia are cut down, the summers (cool as they are) ~ suffice to melt more than the decreased accumulation, and

___

_

_

the glaciers start retreating. The Earth warms up again (as — it is now doing), the Arctic Ocean melts (this point not. yet a having been reached

in the current turn of the cyele), the a

snows begin again, and bang comes another glaciation.

“

But why did all this only start 300,000 years ago? Ewing — a and Donn say because that is when the North Pole first

_

found itself in the Arctic Ocean.

Before then it had been

2 somewhere in the Pacific where the ocean was large enough .

and open enough to cause no severe snowstorms on the dis- — 2 al tant land areas.

a _ Ice Ages could continue to annoy us periodically, then, _ until the present mountains wear down to nubs and th ©

No More Ice ae

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33

ocean bottoms rise, or until the North Pole leaves the Ar (depending on which theory—if either—is correct). - Unless,

that is, something new

interferes,

such

as

“carbon dioxide we are pouring into the atmosphere. The c > rent temperature rise is being radically hastened, apparently, by the increased carbon dioxide in the atmospher The next temperature drop may be correspondingly slowed

vi

_ and may, conceivably, not drop far enough to start a new Sertheretore. it is possible that Earth has seen its last Ice Age, regardless of the Milankovich cycle or the positionof the North Pole, until such time as the ocean, or we ourselves,

can a

get rid of the excess carbon dioxide once again. Within -

matter of centuries, then, we may reverse much or all of

an

80,000,000 year trend of dropping temperature and find our¥ selves back in the Mesozoic, climatically speaking, only withput (thank goodness) the dinosaurs.

o

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3 Thin Air

x

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Earth’s atmosphere is now going through a period—

of scientific importance and prominence. To put it as color-— - fully:(and yet as honestly) as possible, it is all the scientific_

Once before in scientific history, Earth’s

atmosphere

ed through a period of glamour. Let me tell you about ~

before I get to the current period.

a

o begin with, in ancient Greek times, air had all the digof an “element”; one of the abstract substances out of ©

oh the Universe was composed. According to the philoso-—

of

» culminating in Aristotle, the Universe was composed — “earth,” “water,” “air,” and “fire” in four concentric shells, —

ith earth at the bottom and fire at the top.

i.

modern terms, earth is equivalent to the lithosphere, the —

. body of the planet itself. Water is the hydrosphere, or | ; and air is the atmosphere. Fire is less obvious, being — nigh (according to Aristotle) as to be ordinarily imper- — ceptible to human senses. However, storms roiled the sphere — of fire and made fragments of it visible to us as lightning. — _ Even the sphere of fire reached only to the Moon. From ~

_ the Moon outward, there was a fifth and heavenly “element,” —

ce none of those on our imperfect earth. Aristotle called it |

ther.” Medieval scholars called it “fifth element” but did— in Latin, so that the word came out “quintessence.” That |

word survives today, meaning the purest and most essential

partof anything.

SS

Se

—

‘Such a theory as to the structure of the universe presented _ lythinkers with few problems about the*air. For instance, did the atmosphere ever come to an end as one went up-

.

eae

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‘Thin dir © 35

You see, there was always something in the Aristotelian _ view. Just as earth gave way to water and water to air, with no gap between, so air gave way to fire and fire to ether. There was never nothing. As the ancient scholars said, “Na- ture abhors a Vacuum.”

Did the atmosphere weigh anything? Obviously not. You didn’t feel any weight, did you? If a rock fell on you or a bucket’s worth of water, you would feel the weight. But

there’s no feeling of weight to the air. Aristotle had an ex_ planation for this. Earth and water had a natural tendency to move

downward,

as far as they could, toward the center

of the universe (i.e. the center of the Earth).

r

Air, on the other hand, had a natural tendency to move _ upward, as anyone could plainly see. (Blow bubbles under

water and watch them move upward—not that Aristotle would appeal to experiment, believing as he did that the light of reason was sufficient to penetrate the secrets of na-

_ ture.) Since air lifted upward, it had no weight downward. Aristotle

flourished

about

330

B.c.

and his views

were

_ gospel for a long time. Curtain falls. Two thousand years pass. Curtain rises. Toward

the end of his long and brilliant life, Galileo

Galilei, the Italian scientist, grew interested in the fact that

an ordinary water pump drawing water out of a well would not lift the water any higher than about 33 feet above the. natural level. This no matter how vigorously and how per_ tinaciously the handle of the pump was operated.

Now. people thought they knew how a pump worked. It was so designed that a tightly fitted piston moved upward within a cylinder, creating a vacuum. Since Nature abhorred a vacuum, water rushed upward to fill said vacuum and was trapped by a one-way valve. The process was repeated and repeated, more and more water rushed upward until it _ poured out the spout. Theoretically, this should go on forever, the water rising higher and higher as long as you worked the pump. 3 Then why didn’t water rise more than 33 feet above its natural levelP Galileo shook his head, and never did era answer. He muttered gruffly that apparently Nature abhorred

a vacuum only up to 33 feet and recommended that his pupil Evangelista Torricelli look into the matter. . — i In 1643, the year after Galileo’s death, Torricelli did that. It occurred to him that what lifted the water wasn’t a fit of

emotion on the part of Dame Nature, but the very unemoee

ee

ae

=

‘Fact and Fancy

weight of air pressing down on the water and forcing

th

ward into a vacuum

(which would ordinarily be filled —

a balancing weight of air). Water could not be forced

sher than 33 feet because a column of water 33 feet high ed down as hard as did the entire atmosphere, so that was

a balance.

if a complete

Even

were

vacuum

d over the water, so that air down at well-water level

hed the column upward without any back air pressure,

weight of the water itself was enough to balance the

air pressure. _ How to test this? If you could start with a column of wasay, 40 feet long, it should sink until the 33-foot level

—

was reached. A 40-foot column of water would have more’ ~ pressure at the bottom than the entire atmosphere. But how |

to

handle 40 feet of water? Well then, suppose you used a liquid denser than water.

a

at case, a shorter column would suffice to balance airs”

ssure. Fhe densest liquid Torricelli knew of was mercury.

is about 13% times as dense as water. Since 33 divided 13% is about 2% feet, a column of 30 inches of mercury

by

hould balance the air pressure. rricelli filled a tube (closed at one end and a yard long) mercury, put his thumb over the open end, and tipped

_~

to an open container of mercury. If the air had no

veight, it would not press on the exposed mercury level in

Porat All the mercury in the tube would therefore our out.

~~ a

The mercury in the tube started pouring out, to be sure, t only to the extent of a few inches. Fully 30 inches of

| ~

ercury remained standing, supported by nothing, apparey It was either magic or else Aristotle was wrong and

air

the

had weight. There was no choice; air had weight. Thus

first glamorous period of the atmosphere had begun.

ic

had invented the barometer, an instrument still

used today to measure air pressure as so many inches of mer-

, Furthermore, in the upper part of the tube, in the few

thes that had been vacated by the mercury, there wasa\vacuum, filled with nothing but some mercury vapor and little of that. It is called a Torricellian vacuum

ed

jday and was the first decent man-made vacuum

mmied.

It showed

definitely

that

Nature

didn’t

ged, nickel one way or the other for vacuums.

to

ever

give

a

a

In 1650-Otto von Guericke, who happened to be mayor wa

ie German city of Magdeburg, went a step further. He

ed an air pump which could pump air out of an en-

Fees t-? thy ae

ray

Wes

2h, en ae

Th

Pee AG

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Thin Air

closure, forming a harder and harder vacuum;

© 37

i.e. one that

|grew more and more vacuous. _ Von Guericke then demonstrated the power of air pres-— sure in a dramatic way. He had two metal hemispheres made —

which ended in flat rims that could be greased and stuck together. If this were done, the heavy hemispheres fell apart | pf themselves. There was nothing to hold them together. ~ —

But one of the hemispheres had a valved: nozzle to which an air pump could be affixed. Von Guericke put the hemispheres together and pumped the air out of them, then closed the valve. Now the weight of the atmosphere was pressing the hemispheres together and there was no equiva_

dent pressure within.

How

'

i

strong was this air pressure? Well, publicity-wise

von Guericke attached a team of horses to one hemisphere —

_by-a handle he had thoughtfully provided upon it and an-—

other team to the other hemisphere. With half-the town of Magdeburg watching open-mouthed, he had the horses —

Strain uselessly in opposite directions. Sac. ___ The thin air about us which “obviously” weighed nothing — did indeed weigh plenty. And when that weight was put to “use, two teams of horses couldn’t counter it. Von Guericke released the horses, opened the valve, and

_the hemispheres fell open by themselves. It was. as dramatic an experiment as Galileo’s supposed tossing of two balls of — ifferent mass off the Tower of Pisa, and what’s more, von

'

Guericke’s experiment really happened.

(They don’t make

ayors like that anymore.)

- Since the atmosphere has weight, there could only be so _ much of it and no more. There could only be enough of it to allow a column of air (from sea level to the very tiptop), with a cross-sectional area of one square inch, to weigh 14.7 _ _ = pounds. If the atmosphere were as dense all the way up as ~ it is at‘sea level, a column just five miles high would have the "necessary weight. Zr But of course, air isn’t equally dense all the way up. ~

___In the 1650s a British scientist, Robert Boyle, having. read |

of von Guericke’s experiments, set about to study the proper_ ties of air more thoroughly. He found it to be compressible. — ’ That is, if he trapped a sample of air in the short ‘closed. half of a U-tube by pouring mercury into the long, open half, the trapped air contracted in volume (i.e. was: compressed) until it had built up an internal pressure that balanced the head of mercury. As the mercury was-added or removed

@ Fact and Fancy

trapped air compressed and expanded like a spring. The | ‘lish scientist, Robert Hooke, had just been reporting on~ behavior of actual springs and since the trapped air beed analogously, Boyle called it “the spring of the air.” f,now, Boyle poured additional mercury into the U-tube, | apped air decreased further in volume until the internal ~ ssure had increased to the point where the additional “| ght of mercury could be supported. Furthermore, Boyle | 1 2 actual measurements and found that if the pressure on ~

the trapped air was doubled, its volume was halved; if the | pressure was tripled, the volume was reduced to one third

so on. (This is one way of stating what is now called

yle’s law.)

_

©

This was a remarkable discovery, for liquids and solids id not behave in this way. Boyle’s work marks the begin- | g of the scientific study of the properties of gases which, | “in a.hundred years, produced the atomic theory and revolu-

‘tionized chemistry. This was just another consequence of this ‘st glamorous period of the atmosphere. “a _ Since air is compressible, the lowest regions of the atmos-

|

|

here, which bear all the weight of all the air above must ~ be most compressed. As one moves upward in the atmos- ~ phere, each successive sample of air at greater and greater eights has less atmosphere above it, is subjected to a smaller ight of air, and is therefore less compressed. 3 It follows that a given number of molecules takes up more ~ om ten miles up than they do at sea level, and more room still twenty miles up and more room still thirty miles up and ~

so on indefinitely. From this, it would seem that the atmos-

_ phere must

also stretch up indefinitely.

True,

there’s

less

and less of it as you go up, but that less and less is taking aug more and more room. In fact, it can be calculated that, if the atmosphere were

at the sea-level average of temperature throughout its height, _ air pressure would be reduced tenfold for every twelve— “miles we travel upward. In other words, since air pressure is _ _ 80.inches of mercury at sea level, it would be 3 inches of mer_cury,at a height of 12 miles, 0.3 inches of mercury at 24 ©

miles; 0.03 inches of mercury at 36 miles, and so on. % a Even at a height of 108 miles, there would still be, by ©

this accounting, 0.00000003 inches of mercury of pressure. |

_ This doesn’t sound like much, but it means that six million tons of air would be included in the portion of the atmo:

_phere higher than 100 miles above Earth’s- surface. __ OF course, the atmosphere is not the same temperatur ae

-

f nah ee

x

eo

Ni pn

a) Cae

;

ee

-)

ae

Thin Air @~ 39 throughout. It is the common mountain

slopes are

always

experience of mankind that cooler than

the valley below.

There is also no enyee the fact that high mountains are perpetually snow-covered

at the top, even through the sum-

mer and even in the tropics. eG Presumably, then, the temperature of the atmosphere lowers with height and, it seemed likely, did so in a smooth fall all the way up. This spoiled the simple theory of decline of density with height but it didn’t alter the fact that the _atmosphere was remarkably high. Once astronomers started looking, they found ample evidence of that. ; For instance, visible meteor trails have been placed (by _ triangulation) as high as 100 miles. That means that even at 100 miles, then, there is enough atmosphere to friction tiny _ pits of metals to incandescence. =

Furthermore, aurora borealis (caused by the glowing of

on

thin wisps of gas as the result of the bombardment with :— from outer space) has been detected as high as 600 _ miles. ; ; However, how was one to get details on the upper atmosphere? Particularly one would want to.know the exact-way _in which temperature and pressure fell off with height. As _ early as 1648 the French scientist, Blaise Pascal, had sent a

_ friend up a mountain side with a barometer to check the _ fall of air pressure; but then, how high are mountains?

_ The highest mountains easily accessible to the Europeans _ of the seventeenth century were the Alps, the tallest peaks _ of which extend 3 miles into the air. Even the highest moun_ tains of all, the Himalayas, only double that. And then, how could you be sure that the air 6 miles high in the Himalayas was the same as the air 6 miles high over the blank and awe level ocean. om

No, anything in the atmosphere higher than, say, a mile

' was attainable only in restricted portions of the globe and _ then with great difficulty. And anything higher than 5 or 6 _ miles just wasn’t attainable, period. No one would ever know. No one. So the first glamorous period of the atmosphere came to an end. Curtain falls. A.century and a half passes. Curtain rises,

In 1782 two French brothers, Joseph Michel Montgolfier _ and Jacques Etienne Montgolfier, lit a fire under a large _ light bag with an opening underneath and allowed the heated

air and smoke.to fill it. The hot air, being lighter than the

4 8

Fact and Fancy

=

cold air, moved upward, just as an air bubble would move — ‘ upward in water. The movement carried the bag with it, and _ the first balloon had been constructed.

Within a matter of months, hydrogen replaced hot air, gondolas were added, and first animals and then men went

aloft.

In the next few decades,

aeronautics

was

a

an estab-

lished craze—a full century before the Wright brothers.

Within a year of the first balloon, an American named john Jeffries went up in one, carrying a barometer and other

instruments, plus provisions to collect air at various heights. e. _ The atmosphere, miles high, was thus suddenly and spec-

- tacularly made available _ period had begun. _. By 1804 the French had gone up nearly 4% erably greater than that

to science and the second glamorous

3 scientist, Joseph Louis Gay-Lussac, miles in a balloon, a height considof the highest peak of the Alps, and _ brought down air collected there. 3 _ It was, however, difficult to go much higher than that, be- ~ cause

had the inconvenient

the aeronauts

habit of breath- a

ing. In 1874, three men went up 6 miles—the height of Mount Everest—but only one survived. In 1892 the prac- ©

tice of sending up unmanned (but instrumented) balloons ~ was inaugurated. « _ The most important purpose of the early experiments was

_the measurement of the temperature at heights and by the

-

_1890s some startling results showed up. The temperature did

_ indeed drop steadily as one went upward, until at a height

_

greater than that of Mount Everest, the tempera- —

_somewhat

_ ture of —70° F, was reached. Then, for some miles higher, _ there were no further temperature changes.

__ The French meteorologist, Leon P. Teisserenc de Bort, the discoverers of this fact, therefore divided the atoe

_

_ mosphere into two layers. The lower layer, where there was — _ temperature change, was characterized by rising and falling __air currents that kept that region of the atmosphere churned

up and produced clouds and all the changing weather phe_ nomena with which we are familiar. This is the troposphere

~

; _ (‘the sphere of change”). __ The height at which the temperature fall ceased was the _

_ tropopause (“end of change”) and above it was the region __ of constant temperature, a place of no currents or churning, es _ where the air lay quietly and (Teisserenc de Bort thought) in a _ layers, with the lighter gases floating on top. Perhaps the —

__ earth’s atmospheric supply of helium and hydrogen were to Vs Te oa

F

'

’

\

a

Tae,

oh, a

—— 5 aie -

Thin Air

t mee @ 41

¢ found up there, floating on the denser gases below. He” walled this upper layer the stratosphere (“sphere of layers”). — _ The tropopause is about ten miles above sea level at the — eq ator and only five miles above at the poles. The strato- — pphere extends from the tropopause up to about sixteen miles. There, where the temperature starts changing again, — BS

the stratopause.

_ About 75 per cent of the total air mass of the earth exists — within the troposphere and another 23 per cent is in the — $@atosphere. Together, troposphere and stratosphere, with 98

yer

cent of the total air mass between them, make up the

iwer atmosphere.” But it is the 2 per cent above the strato- —

Nause, the “upper atmosphere,” which gained particularb3rominence as the twentieth century wore on.

the 1930s ballooning entered a new era. Balloons of © polyethylene

plastic were

lighter, stronger,

less permeable

—

) gas than the old silken balloons (cheaper, too), They — d reach heights of more than twenty miles. Sealed gon- —

Olas were used and the balloonists carried their own air supply with them. In this way,

manned

balloons

reached

the stratosphere

kand beyond. Russian balloonists brought back samples of — stratospheric air and no helium or hydrogen was present; just ne usual oxygen and nitrogen. (We now know that the at-— a0sphere is largely oxygen and nitrogen all the way up.)

_ Airplanes with sealed cabins were flying the stratosphere,

—

00, and toward the end of World War II, the jet streams fere discovered. These were two strong air currents girdling ne earth, and moving from east to west at 100 to 500 miles | er hour at about tropopause heights, one in the North Temerate Zone and one in the South Temperate. Apparently aey

are of particular importance in weather forecasting, for

hey wriggle about quite a bit and the weather pattern fol lows their wriggling. ‘aoe _ After World War II, rockets began going up and sending — down data. The region above the stratosphere was more and hore thoroughly explored. Thus it was found that from the ~ tratopause to a height of about 35 miles, the temperature-

ses, reaching a high of —55° F. before dropping once more 'to -100° F. at a height of about 50 miles. Above that there a large and steady rise to temperatures that are estimated

~

e about 2200° F. at a height of 300 miles and are prob- |

higher still at greater heights. -- _ region of rising, then falling, temperature, from 16 to — ‘

F

SP

ae ie

ae

42.

©

ps T

Fact and Fancy

. ,

S ” 50 miles is now called the mesosphere (“the middle sphere”)

and the region of minimum temperature that tops it is the” _ mesopause. The mesosphere contains virtually all the mass of)

the upper atmosphere, about 2 per cent of the total. Above”

the mesopause, only a few thousandths of a per cent of the “3 ine atmosphere remain.

These last wisps are, however, anything but insignificant, and they are divided into two regions. From 50 to 100 miles” is the region where meteor trails are visible. This is the ther-_ mosphere (“sphere of heat” because of the rising tempera-_ - tures) and is topped by the thermopause though that is not the “end of heat.” Some authorities run the thermosphere up_ to 200 or even 300 miles. c Above the thermopause, is the region of the atmosphere which is too thin to heat meteors to incandescence but which” can still’support the aurora borealis. This is the exosphere (“outside sphere”). A There is no clear upper boundary of the exosphere. Actually, the exosphere just thins and fades into interplanetary space (which is not, of course,

a complete vacuum).

Some.

try to judge the “end of the atmosphere” by the manner in” :-which the molecules of the air hit one another.

5

Here at sea level, molecules are crowded so closely together that any one molecule will only be able to travel a few millionths of an inch (on the average) before striking another. The air acts like a continuous medium, for that reason. At a height of ten miles, the molecules have so thinned out that they may travel a ten-thousandth of an inch before colliding. At a height of 70 miles, they will travel a yard anda

half and at 150 miles, 370 yards before colliding. At a height of several hundred miles, collisions become so rare that you

can ignore them and the atmosphere begins to behave like a collection of independent particles. (If you have ever been part of the New Year’s Eve crowd in Times Square, and have also walked a lonely city street at 2 A.M., you have an intuitive notion of the difference between particles composing an apparently continuous medium

and particles in isolation.) ‘ The point where the atmosphere stops behaving like a continuous medium and begins to act like a collection of independent particles may be considered the exopause, the end of the atmosphere. This has been placed at heights vary-

ing from 600 to 1000 miles by different authorities. ©

ap pe '¢ ©

1

,

Ye

3

Thin Air

The —

¥

lat it

Hiha

e

ane

importance to us of the upper atmosphere is |

bears the brunt of the various bombardments from

uter space, blunting them and shielding us.

For one thing there is the Sun’s heat. The Sun emits pho- rs

hons with the energy one would expect of a body with the— :

urface temperature of 10,000° F. These photons do not e energy as they travel through space, and consequently trike the atmosphere in full force. Fortunately, the Sun raliates them in all directions and only a billionth or so are ercepted by our own planet. 4 when one of the photons strikes a molecule at the edge of the atmosphere and is absorbed, that molecule may Hind itself possessed of a Sun-type temperature of 10,000° F. nly a small proportion of the molecules of Earth’s atmosohere are so heated and slowly, by collision with other mole-

—

— — ~ —

ules below, the energy is shared so that the temperature

drops to bearable levels as one descends. “4 (The high temperatures of the exosphere and thermosphere _ are an odd echo of the Aristotelian sphere of “fire.” You may

Also be wondering how rockets can pass through the exo-

—

phere, if it has a temperature in the thousands of degrees,

fithout being destroyed. There you run up against the fference between temperature and heat. The individual —

a0lecules have much energy, i.e. have a high temperature,

mat there are so few of them, that the total energy, i.e. heat, is negligible.) -Of course, the high temperature of the outermost atmos- —

Mphere has its effects on the molecules that compose it. Oxyen and nitrogen molecules, shaken by this temperature and Xposed to the bombardment of high energy particles beside, ibreak up into individual atoms. (If the free atoms sink down tto positions where less energy is available, they recombine, SO

NO permanent damage is done.)

People have wondered whether ram-jets might not make | use of these free atoms to navigate the exosphere. If enough

‘could be gathered

and compressed

(and that is the hard

yart) the energy delivered per weight by their reunion to form molecules would be much higher than the energy dellivered per weight by the combination of conventional fuels \ with oxygen, ozone, or fluorine. Furthermore, the supply would be inexhaustible, since the

toms, once combined into molecules, would be expelled out he rear where the Sun’s energy would promptly split them into toms again. In effect, such a ram-jet would be running on

energy, one tiny step removed,

oe

i

res

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on

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ja

Bee 44. ¢ "s .

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The

i

Fact and Fancy

rod bombardment

ae’ >:

”

+

.

Ri;3 bE of particles from space also succeeds — :

in damaging individual atoms or molecules, knocking off one 3 or more planetary electrons, and leaving behind charged : atom fragments called ions. Enough ions are formed in the mt a _ exosphere to produce the glow called the auroras. In the denser air of the thermosphere, there are more or ~ less permanent layers of ions at different heights. These first ~ made themselves known by the fact that they reflect certain — radio waves. In 1902 Oliver Heaviside of England and Ar-_ : thur Edwin Kennelly of the United States discovered (inde- < ~ pendently) the lowest of these layers, about 70 miles high,— = eo it is called the Kennelly-Heaviside layer in their honor.

y

Higher layers (at about 120 miles and 200 miles) were discovered in 1927 by the British physicist, Edward Victor Ap-— _ ~ pleton, and these are called the Appleton layers. Because of ~ these various

layers of ions, the thermosphere

is frequently —

called the ionosphere, and its upper boundary the iono-— pause (though that is not the “end of ions” any more than — - the “end of heat”).

,

Nowadays, the layers have received objective letters. The Kennelly-Heaviside

layer is the E layer, while the Appleton

—

layers are the Fi layer and Fe layer. Between the Fi layer _ and the E layer is the E region and below the E layer is ~ the D region. Yet lower in the atmosphere, down in the mesosphere, the — ultraviolet of the Sun is still capable of inducing chemical reactions that do not ordinarily proceed spontaneously at sea_ ; ‘level. It is possible to send chemicals up there and watch” things happen. In the main, though, the important point is _ that something happensto a chemical already present there. Ordinary oxygen molecules of the mesosphere (made up of. two oxygen atoms apiece) are converted into the more energetic ozone molecules (made up of three oxygen atoms apiece). The ozone is continually changing back to oxygen while the forever incoming ultraviolet is continually forming more ozone. An equilibrium is reached and a permanent layer of. ozone exists about 15 miles above the Earth’s surface. This is fortunate for us since the maintenance of. the ozone layer

_ continually absorbs the Sun’s hard ultraviolet which, if it

were

allowed to reach the Earth’s surface-unabsorbed, would

be fatal for most forms of life in short order. . Because of the chemical reactions proceeding in'the meso+ sphere it is sometimes called the chemosphere (and its upper ~—-_F

—

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Thin Air

hae,

> chemepause). As for the ozone layer it

Sees al

:

ace “this side of ths Moon’ ni richhas Se "ica a knowledge of the existence of the Van Allen ‘ on belts—and what else?

r 4 Catching Up with Newton é

It is very irritating that, in this modern er missiles and satellites, there are so many newsmen w. haven't caught up with Newton yet. They speak with ap

_ ing glibness about the weightlessness experienced by.a sp _man once he has climbed “beyond the reach of gravit pas cosemably they have the impression that there is a bounda _line near the top of the atmosphere or thereabouts, beyond which there is suddenly no gravity—and that is the very _ thing Newton’s theory disallows. Isaac Newton was the first to formulate the Law of Un es ‘sal Gravitation. Note the adjective “Universal,” which is

important word. Newton did not discover that apples fell the ground when they broke loose from the tree; that was common knowledge. What he did demonstrate was that th Moon’s path around the Earth could be explained by sup _ posing that the Moon was in the grip of oe same force og ~ tugged at the apple. His great suggestion was that every piece of matter in the Universe attracted every other piece of matter, and that the - quantity of this force could be expressed in a simple formula The force of attraction (f) between any two bodies, saic Newton, is proportional to the product of the masses (mi anc me) of the bodies and inversely proportional to the square o _

the distance (d) between their centers. By introducing a pro

portionality constant (G), we can set up an eee

senting the above statement symbolically:

f= Gmimo/d?

rep

(Eatiaton J

The most recent and presumably most accurate value ob ;.tained for G (in 1928, at the-Bureau of Standards) is6. 46

;

Pe

eS

a

ee

Catching Up with Newton e

x10 dyne cm?/sec?. This means

that if two

4T

1-gram_

ppherical masses are placed exactly 1 centimeter apart (center to center), the attraction between them is 6.670 x 10°

S. This shows gravity to be a relatively weak force as com-

ad

ed with electrical and magnetic attractions, for instance.

‘one dyne of force is equivalent, roughly, to 1 milligram of

x

4

weight. If the two 1-gram spheres were the only matter in tthe universe, therefore, each would weigh, under the gravi- 3 fational attraction of the other at the distance indicated, only_ 10.000000066 milligrams (or about two trillionths of an ounce). 3 Jowever, when masses as large as the Earth are concerned,

en a weak force like gravity becomes tremendous.

+ 4 _ Of course, we don’t have to use dynes or any other re aits to understand the essentials of gravity. Suppose, for— ance, that the two masses between which we are trying —

|}measure gravitational attraction are a spaceship and the et Earth. The mass of the spaceship we can set equal — (one what? one spaceship-mass). The mass of the Earth ©

:can also set equal to 1, by using different units—one

©

arth-mass, this time.

_ The distance between the center of the Earth and the cen- © er of the spaceship, which we will suppose to be resting on he Earth’s surface, is just about 3950 miles. We can make this value also 1 by calling that number of miles 1 Earth- — ‘radius, Notice, now, that in using Newton’s equation, it is necesisary to take distances from center to center. In other words, —

theimportant point is not how far the spaceship is from

e surface of the Earth, but how far from its center. It is one of Newton’s great accomplishments, you see, that fe was able to demonstrate that spheres of uniform density | each other as though all their mass were concentrated the central point. To be sure, actual heavenly bodies are

ot uniformly dense, but Newton

also showed this central-

ie business to be true for spheres which consisted of a eries of layers (like an onion) each of which was uniform in density, though the density might vary from layer to layer. _ This modified situation does hold true for actual heavenly odies.

"But back to Earth and spaceship. Now that we have chosen 4 eet for masses aud Se, it is only neces-

—

.

@

‘

.

Fact and Fancy

sary to make the gravitational constant-also 1 (one constant-

___ yalue) and Equation 1 becomes: 1 >&

,

ees ae

a

is

=

¥

ee

:

(Equation2)

f=1x1xV/P ja

‘

a

as the result of our shrewd unit choices, it turns:

Therefore,

__ out that the force of attraction between Earth and space= i

__. ship is exactly 1.

_ So far so good, but this is for the spaceship resting om

~

* Earth’s surface. What if it were not on Earth’s surface but = 8950 miles straight up? “By ‘changing the spaceship’s position, we are not alter= - . ing its mass, or Earth’s mass or the gravitational constant.

Each

of these can remain 1. The only thing

that is being

altered is the distance between the center-of the spaceship

_.

and the center of the Earth, so distance is all we need con-

_ cern ourselves with and Equation 2 becomes: .

€ 4

L

:

f = 1/d?

(Equation 3)

_ Now, then, if the spaceship is 3950 miles above the Earth’s Surface, its distance from the center of the Earth is .3950 miles plus 3950 miles or 2 Earth-radii. (We can use any ___units we want but, once having chosen them, we must stick ___ with them. Such are the ethics of the situation.) y . At 3950 miles above the Earth’s surface, then, the force of

___ attraction between Earth and the spaceship, using Equation 3,

is 1/22 or 0.25.

.

;

Gravitational attraction is usually measured by weighing ' ~ an object. Consequently we can say that whatever the weight __ Of the spaceship on the surface of the Earth, it weighs (i.e. i

_ is attracted by the Earth) only % as much 3950 miles above

the

--

surface. By the same reasoning we could show that this would hold for any object other than the spaceship. The -gravitational attraction of the Earth for anything at all drops to 4

+

quarter of its value as that “anything at all” is moved from

_. Earth’s surface to a height 3950 miles above its surface. Equation 3, will also give us the force between the Eartk

+ and the spaceship (or any other object) for any height above _ ~~» the surface. Some figures, so obtained, are shown in Table 1 __

|

___As you see, gravitational force starts dropping off at once

Even at low satellite-heights, so to speak, it varies from % te

__ %o of what it is at the planet’s surface. Or, to get really a

Catching Up with Newton.

@- 49

| about it: if you weigh 150 pounds and are suddenly trans-

_ ported to the top of Mount Everest from your sea-level home, _ you would find gravity weakened enough to make your weight 149% pounds. Be 2 Nevertheless, Earth’s gravitational force does not drop to. zero, no matter what the distance. No matter how large you made d in Equation 3, f is never zero. If you go back to Equa_ tion 1, you would see that this is also true for the attraction between any two bodies, however small, with masses greater than zero. In other words, the gravitational influence of

every body, however small, is exerted through all of space. Nor does the force very quickly become negligible when large bodies

are involved.

The

gravitational

force between

Earth and Venus, at closest approach is only 0.000000025 that of. what it would be if the two planets were in contact. Nevertheless, the force attracting the Earth and Venus, even at a distance of 25,000,000 miles is still equal to 130. trillion tons. So much

'

for spacemen

getting

“beyond

the

reach

of

avity.”

The word “Universal” in Newton’s law wouldn’t be worth

‘much, if we don’t apply the equation to other bodies. We can start by supposing the spaceship to be resting on the surface of the Moon. To begin with, the spaceship has the same mass (i.e. the quantity of matter contained in its substance) as on Earth “and we agreed to let that mass (m1) equal 1. The constant G

never varies and we agreed to let that equal 1, also. Equa‘tion I therefore becomes:

{= m2/d?

~

(Equation 4)

where me is the mass of the Moon and d is the distance from the center of the spaceship to the center of the Moon. Since

the spaceship is on the Moon’s surface, d is equal to the radius of the Moon.

-

We've defined our unit for mz as “Earth-masses” and for ‘d as “Earth-radii,” and we will stick to that. The Moon is only 0.0123 (about %1) as massive as the Earth and its radius” is only 0.273 (a little over 4) that of the Earth. _ The Moon’s mass is therefore 0.0123 “Earth-masses” and its radius 0.273 “Earth-radii” so that Equation 2 becomes:

>

f = 0.0123/0.273% = 0,164

(Equation 5)

|

‘a

:

/

|

|

oe

9

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do:

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7 Catching Up with Newton

This means

©

51

that whatever the spaceship weighs on ~ .

surface of the Earth

as the result of the force of Earth’

. gravitational attraction, it weighs 0.164 times, that (roughly

_¥%) on the surface of the Moon, as the result of the Moo: 1§

(lesser) gravitational attraction. By the same reasoning, this ratio of weight would hold true for any object at all. : Given the mass and radius of any body, the value of the

“m

surface gravity of that body can be calculated in the same way. The surtace gravity of various bodies in the Solar System is presented in Table 2 by way of example. Notice that Jupiter and Saturn are not perfect spheres. Both are noticeably flattened at the poles. Saturn is the least

spherical of the planets, there being a 12 per cent difference _ between the polar radius and the equatorial radius. For Jupiter, there is a 7.5 per cent difference. In both cases, since

d varies with latitude, so does surface gravity, being least at _ the equator and highest at the pole. (The equatorial gravity is further decreased by the centrifugal force of the planet's spin, but I’ve ignored that here. Enough is enough.) . The fact that Saturn, which is so much more massive than

Earth, has a surface gravity only slightly higher is not mysterious. Saturn is only 4% as dense as Earth and is correspondingly more voluminous than it would be if it were made of Earth-type material. The effect of the abnormally large radius for Saturn’s mass (as compared with Earth) is to lower the surface gravity because of increased distance be_ tween Saturn’s center and an object on its surface by just about as much as Saturn’s increased mass (over Earth) raises

it

Surface gravities of Saturn and Earth may be approxi-

mately equal but this is illusory, in a way. Look at it this A spaceship on a planetary surface is at varying distance ~ from

that planet’s

sizes. Suppose, from

Earth’s

center,

since

planets

come

in different

though, that a spaceship is 230,000 miles center

at one

time

and 230,000

miles from

Saturn’s center at another. "ae When it is 230,000 miles from Earth’s center it is about 226,000 miles above its surface. At 230,000 miles from _Saturn’s center, it is only 192,000 miles above its surface,

_ Saturn being the larger body. However, in considering gravi_ tational force, as I have pointed out, it is distance from the | See that counts, ; xe ’ Cae

:

-

ee

ae

f

:

|

ies}

ae

i)

&

:

n re}5 oO

Ss

(

=e far&

3

a

ot

o, =]

wm

3

Mass (IN EARTH-

ive} : Radius (IN EARTH-

Surface

MASSES )

RADII)

gravity

iter (pole)

318.

10.5

2.88

iter (equator) ptune

318. 17.3

11.2 3.4

2.54 150

95.2

9.5

turn (pole)

turn (equator)

ot

2

|?ih 8

npr

0.11

-

"ae

1.0535

3.7 1.0 0.96

1.05. 1.00 0.89

0.525

0.054 0.026 0.0123

kPAa ge>

1.3299

8.5

14.5 1.0 0.82

afk

0.40

0.380 0.395 0.273

0.27. 0.17 0.16

a

q

In such a case, with d equal in the two situations, only me oe | (see Equation 4) remains to vary the result. Earth’s mass is, . | of course, equal to 1 “Earth-mass.” Saturn’s mass is 95.2

_

“Earth-masses.” Therefore, the gravitational force gripping hespaceship in the neighborhood of Saturn is always 95.2 > imes that gripping it at an equal distance from Earth. a | This can be shown in the behavior of two satellites that ~ | happen to be at this distance from Earth and Saturn. The —

| Moon is at an average distance of 239,000 miles from — Zarth’s center, while Saturn’s satellite Dione is about 230,000

miles from Saturn’s center. Each travels just about 1,500,000 _ miles in completing its circuit about its primary. 13

_ The greater the force of gravitational attraction upon a _

» Satellite, the faster must that satellite move to work up. — } enough centrifugal force to keep in its orbit against its planets pull. The Moon can manage this by traveling at a rate — f 2200

miles an hour and completing its revolution in a _

isurely 27,32 days. Dione, however, must race along at — t ten times that speed to stay in orbit. Its period of revotion is only 2.74 days. That, and not the surface gravity figures, is a measure of e force a spaceship would be fighting if it were maneuverg in the neighborhood of Saturn. . .

_

Nevertheless, however great the gravitational force exerted_ y a planet, and however close to it a spaceship may be, it ie why

I"

{ ae

|r

Catching Up with Newton

@

53

‘remains possible for the spaceship (and the people on it) to :

be weightless. And this does not mean that the force of grav_ ity has been suspended. ;

_ Gravity is a force and a force is defined as something that— can accelerate a mass. That, so to speak, is gravity’s main

job. It is what it is doing constantly all over the Universe.

We ourselves happen to be most used to gravitational -

force in its manifestation as the sensation of weight. Actually | this type of manifestation occurs only in a special case: where a body is prevented from responding to gravitational force by accelerated motion. (Accelerated motion, by the way, is — ‘Motion that is continually changing either in velocity or in . direction or both.) rs E. _ The most common way in which accelerated motion can be | ' prevented is by having the two bodies between which the | Qravitational force exists (i.e. a

spaceship and Earth) in con-

‘ tact so that neither can move with respect to the other under ‘the pull of gravitational force alone. You and I are almost — ‘ always in contact with Earth and it is for that reason that ‘we es to think of gravity as primarily concerned with ’ weight.

:

Yet we live with the acceleration too. Hold a book at arm ‘level and let go. At once gravitational force expresses itself :in terms of acceleration. The book accelerates in the direc-

tion of Earth’s center and keeps on until the surface of the © ;planet intercepts it and it can move no more. _ The Moon, as it moves about the Earth, is undergoing ac-

: celerated motion since, moving in an ellipse as it does, it is | continually changing direction, turning a full 360° in 27.32 | days. (It also continually changes velocity to a comparatively. ‘minor extent.) Dione, under the whip of a stronger gravitational force, is more strongly accelerated, changing direc--

‘tion more quickly and turning 360°; as I have said, in only — 2.74 days. . ’ Whenever a body like*a book or a Satellite is responding to gravitational force by unrestricted accelerated motion, it is said to be in “free fall.” The word “unrestricted” in the previous sentence is a bow in the direction of air resistance. A book falling from your hand ought to be moving through a vacuum to be in true free fall. An object moving in response to gravitational force, with

another constant (i.e. non-accelerated) motion superimposed, » _is still in free fall. A missile, with its charge expended, mov-

| geo a direction more or less opposed to that induced by

>

_@

Fact and Fancy

%

"gravity; or a satellite (artificial variety), with its rocket stages— one, and with a component motion perpendicular to— at imposed by gravity—both are still in free fall, = = _An object which is completely in free fall is responding to

ravity all it can; it has no response left over, so to speak,” o be manifested as weight. An object in free fall is there-_ ore weightless. A Cosmonaut orbiting the Earth in a satellite emains weightless as long as he stays in orbit. Gherman ~ itov remained weightless in this manner for a full day. For

that matter, if the cable of an elevator broke

and it fell~

freely with unfortunate you inside, you would be as weight-

ess for a few seconds (barring air-resistance effects) as any

man in orbit in outer space. ‘“ ___ If you were falling at an acceleration greater than that im-

me oced by gravity (as in an airplane power dive) you would— _ feel “negative weight.” Within such a power-diving plane, | you would fall upward. at-increasing speed (relative to the” slane) unless you were strapped into your seat. This is one ‘Kind of “anti-gravity” which may not be useful but which is” at least completely valid. =

_

In calculating the force of gravity at various distances from Earth and on the surface of various planets, I have compared|

these with the intensity of gravitational force on Earth’s sur=

_face, which I arbitrarily set equal to 1.

|

*

But it is easyto measure the actual value of the gravita-

tional force at Earth’s surface. Since forces are measured by’ | the accelerations they induce, it is only necessary to meas| __ure the acceleration of a body dropping, let us say, from

| __ the top of the Empire State Building to the ground under the }

influence of gravity. It turns out that this acceleration and,

|

therefore, the value of the gravitational force (at the equator,

| _at sea level, and corrected for the effects of air resistance) is |. 980.665 centimeters per second per second, or, in more famil-

. | iar units, 31.6 feet per second per second. thy | _ This means that if an office safe is raised to a height o} | __ 5000 feet above the Earth’s surface and released, it would fall

at the rate of 31.6 feet/sec after one second, twice that (63.2 _. feet/sec) after two seconds, three times that (94.8 feet/sec) . after three seconds, and so on, its rate of fall increasing | __ smoothly with time. (Here and elsewhere in this chapter, I

_

|

am ignoring the effects of air resistance, which is a sub-

___versive influence and a nuisance.)

_

a

The equation relating the distance (s) through which ¢ Rae

ee vy

. Catching Up with Newton

a

+

@ ee 5

body falls during a time (t) under gravitational acceleration

(g) is:

|

s = kgt?

2

‘(Equation 6)

The value of g is, of course, 31.6, and if a body is falling from 5000 feet above Earth’s surface, s is 5000. By substi-

tuting these figures into Equation 6, it can be solved for ¢. It turns out that it will take our office safe 17.8 seconds of fall before it splashes into Earth’s surface. At the time of contact, it will be moving 17.8 X 31.6 or 562.5 feet/sec (or 0.106 miles/sec). : : (It does not, by the way, matter, whether we use a golf

ball or an office safe as the falling object. The inertia of an object varies directly with its mass, which means it takes

twice the force to accelerate a two-pound weight at a certain rate as it does to accelerate a one-pound weight. But gravitational force also varies with the mass of the falling object. A two-pound weight is attracted to Earth with twice the force of a one-pound weight. Generalizing this, you can see that the end result is that all objects, whatever their mass,

experience the same- acceleration in a given gravitational field. The effect of air resistance on light objects, such as feathers and leaves, obscures this fact and misled Aristotle—

who thought a two-pound weight fell with twice the acceleration of a one-pound weight—and all who followed him down _to the time of Galileo.) The figures on fall under gravity are true in reverse also, _ If a cannonball is shot directly upward against Earth’s gravity, at a velocity of 0.106 miles/sec as it leaves the cannon’s

mouth, it will travel upward (slowing constantly) for 17.8 ‘seconds and reach a height of 5000 feet before coming to a halt and beginning to fall back. If our original office safe were raised to a height of 20,000 feet instead of 5000, the time of fall would then be 35.6 sec-

onds and the final velocity is 0.212 miles/sec. And if the cannonball were shot upward at an original velocity of 0.212 miles/sec—but you can see that without my telling you. It follows, generally, from Equation 6, that the time of

fall and the final velocity of a falling object, vary as the Square root of the distance of fall, assuming a given constant value of g. It would seem then that the final velocity at contact of office safe and Earth could be as high as you |. care to make it—by setting the safe to falling from a greater __and greater height above the surface.

56

e BBut

@

;

Fact and Fancy

there’s a catch. I said we must assume “a given con* stant value of g,” and that is exactly what we can't do.

The value of g varies with distance from the Earth’s cen- _ r, as I explained earlier. In lifting an office safe, or a golf _ , 5000 or even 20,000 feet above Earth’s surface, the —

stance from Earth’s center is not significantly changed, and — you can work your calculations as though g were constant. — But suppose you were to release your object 3950 miles — above

the surface

of the Earth.

Up there, the value

of 2%

only 9.25 what it is on the surface and the acceleration~

imposed upon a falling body is likewise only 0.25 what it — is here on the surface. PP ~ To be sure, the value of g increases as the object drops ~ and is a full 1 g by the time it is at the collision point. Never- — _ theless it takes longer for the object to complete its drop — than it would have if the value of g were 1 all the way — _ down, and it doesn’t hit at as high a velocity as it would — if the value of g were 1 all the way down. e ___ Eyery additional thousand miles upward from Earth’s sur- — _ face adds less and less to the final velocity. The result is a ©

__ This figure might be called the “maximum final falling ve-— locity,” but it isn’t. People prefer to look at it in reverse. _ If a cannonball, a spaceship, or anything else were fired _ directly upward at a velocity of 6.98 miles/sec (or more), | it

would continue moving outward indefinitely, if there were

—

no interference from extraneous gravitational fields. (Since — a fall even from an infinite distance could not create a final —

_ speed of more than 6.98 miles/sec, then the reverse follows: _ An initial speed of 6.98 miles/sec or more could never be re- —

_

duced to zero by Earth’s gravitation, even

if the object

__ traveled forever.) % An object hurled out in this fashion would never return to

_ Earth. It will not have escaped from the influence of the — __.Earth’s

gravitational field

(which

will be slowing it con-~

stantly) but it will have escaped Earth ‘itself. a _ So the velocity of 6.98 miles a second is the “escape ve-locity” for Earth. ' aie Be The value of the escape velocity varies with the mass ol 4 Po

Catching Up with Newton

© 57 > Sal

he attracting body and the distance from its center as fol-a = ows: va t

v= 6.98 \/ m/d

(Equation 1)

vhere v is the escape velocity, m is the mass of the attracting jody in “Earth-masses” and d the distance to the center of os ihe attracting body in “Earth-radii.” The factor 6.98 allows — ihe escape velocity to come out in miles per second. e

aa

‘The Moon, for instance, has a mass equal to 0.0123 iHarth-masses” and, at its surface, the distance from its cen-

se is 0.273

“Earth-radii.”

The

escape

velocity from

the —

Mfoon’s surface is therefore 6.98 & 1 0.0123/0.273, or 1.49 niles/sec. The escape velocities at the surface of any body in the

colar System can be similarly calculated and the results are presented in Table 3.

‘One caution: Escape velocity is required for escape from a hlanet only where unpowered

(i.e. “ballistic”) flight is con-

—

serned. If you are in a spaceship under constant power, you f . . . 1am move any finite distance from Earth at any velocity eelow escape velocity but above zero, provided you have

wel enough. (In the same way, you cannot jump to a second tory window at a bound unless the initial thrust of your — eg muscles against the ground is great enough—which is nore than you can manage—but you can nevertheless walk ip two flights of stairs as slowly as you please.) And yet escape from Earth may be not entirely escape, fither. I said earlier that an object hurled from Earth at aore than escape velocity would move

here were

no interference

from

outward forever “if

extraneous

—

gravitational

elds.” _ TABLE 3 Escape Velocities at the Surface of Bodies in

:

the Solar System

ig

_ Astronomical 5

Body

ee)

upiter (equator)

aturn (pole) 2 (equator) | Sa

niin a

ae

Radius

(EARTH-

MASSES )

RADII)

318.

10.5

318.

11.2

——

upiter (pole)

te

Mass

(EARTH-

95.2 95.2

aC AT Bie tos al

soe

8.5 29:5

3.4

Escape Velocity

(MILES PER SECOND )

ee

38.4

. 37.3 -

23.4 OD

15.8

ia

. |

58

oa

i

°

Fact and Fancy

‘Uranus. Earth

445 1.0.

Venus Mars Mercury ds Moon. —

But, of course,

‘

2

0.82 OLE ~ 0.054 0.026 0.0123

13.9 6.98

3.7 1.0 0.96 0525 0.380 0.395 0.273

there is such interference.

* ;

6.463.20mi 2.64. 1.80 1.49

Consider the

Sun, for instance, which so far we haven't done.

The Sun has a mass that is equal to 330,000 “Parthe masses” and a radius equal to 109 “Earth- radii.” Using Equation 7, the escape velocity from the Sun’s surface turns out to be a tidy 385 miles/sec. From Earth, however, the distance to the Sun’s center is

about 23,000 “Earth-radii.” Substituting that figure for d in

Equation 7, and leaving m at 330,000 “Earth-masses,” it turns out that the escape velocity from the Sun at Earths -. distance is 26.4 miles/sec.

_

This is four times as high as the escape velocity from

Earth itself. In other words, a missile shot out from Earth and attaining a velocity of 6.98 miles/sec by the time the

rocket thrust is expended, may be free of the Earth, but ét é _ not free of the Sun. It will not recede forever after all, but will take up an orbit about the Sun.

To escape from the Solar System altogether, a speed oO

‘26.4 miles/sec must be attained in ballistic flight. To be sure

_

in powered flight, we don’t have to attain escape velocity; we can just keep the engines going. However, the escape veloc ity is a measure of the amount of energy we must use t break the gravitational chains in any fashion. So you see, i ds the Solar prison bars that block our way to the stars fa

more than Earth’s puny fence. The only consolation

is that, for the moment, the Moor

and the planets are enough of a ‘challenge. The stars can wait

Bate oF a jocs 4 ,-

5 Of Capture and Escape

ee te en Since January 2, 1959, the Soviet Union and the esS te nited States have sent up a number of missiles which were eee yotable for three things: {1) They reached and passed the orbit of the Moon. (2) They were not captured by the Moon; that is, they id not take up a closed orbit about the Moon alone. (3) They took up a closed orbit about the Sun and bei ye a! ame artificial planets. Id like to consider each of these points in turn.

First, what does it take to reach the orbit of the Moon

y means of a ballistic missile? (A ballistic missile is any rojectile which receives an initial impulse of some sort and i aia moves under the influence of gravitational forces nly.

ea we

If such a missile is fired straight up (ie. directly away

rom Earth’s center) the maximum height it will reach will lepend (a) on the strength of the initial impulse upward

a (b) the strength of Earth’s gravitational pull downward. Naturally, the greater the initial impulse upward, the _ reater the height reached. You might expect that doubling he initial impulse will double the height reached, but that

5 too pessimistic. It would be so if the gravitational force emained

constant

all the way

up,

but it does not. The

igher the missile reaches, the weaker the gravitational drag pon it. The second half of its climb meets less resistance herefore and is correspondingly extended. Consequently, doubling the initial impulse more than doules the maximum height reached, and the more you increase he initial impulse, the more drastically do-you increase the maximum height reached. eee 1 gives the maximum height attained for various

_>

rea ty ai

‘

2

’

,

ds.

Bie

f 60

©

d

Fact and Fancy

a ?

— “ea

Pre

oF

— — ©

{ ‘@ initial velocities of the missile. The initial velocity is a measP ure of the strength of the push given the missile. (Naturally, beoe there are complicating factors. There is air resistance; there is the fact that the push of the rocket motors isn’t administered instantaneously, but is spread over several minutes, and so on. Since we're all friends here, I’m taking the privilege

of

—

ignoring such matters and leaving them to the missile en-

gineers, who are most welcome to them.)

_

_

Notice how quickly the maximum height increases, espe-_ cially at speeds higher than 6 miles a second, or, if you~

___ prefer,821,600 miles. an hour. (I have always had a liking for __. the use of “miles per second” as the unit for high velocities,

_ but to a nation of automobile drivers “miles per hour” seems more natural. Besides, newspapers and allied information- mongers use “miles per hour” exclusively, perhaps becauselarger and flashier numbers are involved. So I'll use both” _ units throughout. -I just wish to warn you, though, that 21,600 miles an hour may sound flashier second, but the two are entirely equivalent.)

than 6 miles a’

:

A missile leaving Earth with an initial velocity of 6.92. miles a second (24,912 miles an hour) will reach a height of 220,000 miles before coming to a halt and beginning to fall

> back. This is just about the distance of the Moon at its” closest approach (“perigee”) to the Earth. . __

If, miles Short miles

however, the missile leaves Earth at a velocity of 6.90. a second (24,840 miles an hour), it falls 50,000 miles of the Moon. A difference of 0.02 miles a second (72. an hour) to begin with means a 50,000 mile discrep-

ancy to end with.

re TABLE

1

Maximum Height above

Initial Velocity of Missile nr (MILES PER SECOND)

ee (MILES PER HOUR)

1 2 3 4 5 5.5 te

3,600 7,200 10,800 14,400 18,000 19,800 21,600 23,400

es

Oe (MILES)

~

80 350 900 1,940. 4,180 6,450 § 11106 25,800

® c

-2

as

‘ec Ps

cee

,

\e. 66 i= 6.7 E68 6.85 6.90 6.92 6.95 6.98

Of Capture and Escape

23,760 24,480 24,660 24,840 24.910 25,020 25,130 24,120

®

2 3

34,300 73,600 102,800 170,000 221.000 454,000 a 46,300

Tt is for this reason that when one of our early Moon- _ wobes only reached a third of the way to the Moon, it did jot mean we had only attained a third of the necessary — 2locity. Actually, we had attained over 98 per cent of the “ecessary velocity. It’s just that the last per cent or so is what atries the missile the remaining two thirds of the way to the — {foon. To go back to Table 1, a missile leaving Earth at a veloc- _

gy of 6.98 miles a second (25,130 miles an hour—or somening like 216 miles an hour faster than is required to reach ne Moon’s orbit) has no maximum height. If you like, its aaximum height is infinite, symbolized as © in the table. uch a missile would move

away from Earth forever, as-

uming there is no interference from gravitational fields of ther bodies. The velocity of 6.98 miles a second (25,130 niles an hour) is therefore the “escape velocity” from Earth’s

uarface. Imagine a missile that has left the Earth’s surface at just he escape velocity. As it travels away from the Earth, its ielocity decreases inversely as the square root of its distance rom Earth’s center. (When the distance has been multiplied

"y 4, the velocity has been decreased by 2.) The result is

lhown in Table 2. Earth’s gravitational pull is constantly decreasing the mis- _ ile’s velocity, but with increasing distance, the pull loses

»ower and decreases the velocity at a slower and slower ate. The velocity therefore gets closer and closer to zero s the missile recedes from Earth, but never quite gets to er0. ‘If the missile had left at less than the escape velocity, farth’s gravity would have managed to bring the missile’s elocity to zero at some finite distance and the missile would hen fall back. If the missile leaves at a speed greater than

he escape velocity, its velocity decreases and decreases with

listance but never falls below a certain velocity, greater an zero, however far it travels. (All this-assumes the presae

4

62

@

Fact and Fancy

:

4

q

ence of no other gravitational fields in the Universe, gum= s ming up the ate. j x Let’s put it another way. A missile leaving Earth at a ~~

velocity less than the escape velocity follows an elliptical orbit. An ellipse is a closed curve, so that the missile does - “not depart more than a certain distance from the Earth. If the elliptical orbit happens to intersect Earth’s surface, the ;

ee

_

‘missile crashes its first time round, as our first Moon-probes

~ did. If the elliptical orbit does not intersect the Earth’s

surface, artificial satellites are the result.

a i

=

.

TABLE

S

2

. a

;

Se

.

“a :

Distance from the Genter of the Earth .

Velocity of Missile Fired — at Escape Velocity

question. ) 4 _ As the planet approaches the Sun it spends less and less— time in the night sky and more and more time in the day | sky. For ordinary planets this means it becomes less and less — visible to the naked eye because it is lost in the Sun’s glare — during the day. Even the Moon looks washed out by day. But Sun B would be different. Considering that it is 150

times as bright as the full Moon, it would be a clearly visible— point of light even by day. Allowing the use of smoked — glasses, it could be followed right up to the Sun. ESS Now the Greeks had a myth about how mankind learned ~ the use of fire. At the time of creation, man was naked, shivering, and miserable; one of the weakest and most poorly om

endowed of the animal creation. The demigod Prometheus — had pity on the new creature and stole fire from the Sun to ‘give to mankind. With fire, man conquered night and winter— and marauding beasts. He learned to smelt metals and de-— veloped civilization. 3 _

But the anger of Zeus was kindled at this interference, _ Prometheus was taken to the very ends of the earth (which, —

‘to the Greeks,

were

the Caucasus

Mountains)

and

there

chained to a rock. A vulture was sent there to tear at his —

liver every day, but it left him at night in order that his —

liver mi.t miraculously grow back and be ready for the next day’s torture. b There now. Doesn’t all this fit in perfectly with the appar- _ ent behavior of Sun BP Every year Sun B commits the crime of Prometheus. It can be seen in the daytime approaching — the Sun, the only planet that can be seen to do this. It can _

only be planning to steal light from the Sun, and it obviously _

succeeds. After all, isn’t that why it is so much brighter than— all the other planets, why it is so much brighter even than _

the Moon? aaa Moreover, it brings this light to mankind, for when it is in —

pee nisht sky, it illuminates the landscape into a dim kind

eae

.

° a

~

hed. It is cast out to the edgeof — aievar Wi

he

“a &

a

e@

ei

Fact and Fancy

= universe, further away than any other planet. There is — ee even a vulture tearing at it, in the shape of its clearly visible °

‘satellite. While the planet was busy stealing fire from the

no satellite was visible (because it was drowned out by = - the Sun’s glare, of course). Once the planet was hurled to the

_ edge of the universe, though, and became visible in the night —

_ sky, its satellite appeared. The satellite swoops toward the _ bright planet, tearing at it, then moves away to allow it to

_ recover, then swoops ; rh

in again, and so on in an eternal

With all this in mind, isn’t it just about inevitable that if Sun B were in our sky, it would be named Prometheus? Or _ that the satellite would now have the Latin name Vulturius. i Now I’m far too sober-minded and prosaic myself to think ~ outlandish thoughts (as all of you know), but I wouldn’t be

surprised if some people reading this might not think the ‘i parallelis far too close to be accidental. Could it be that such a heavenly situation actually existed and suggested the _ myth in the first place? “Could it be that the human race originated on a planet

|

circling Alpha Centauri AP Could they have migrated to Earth about fifty thousand years ago, wiping out the primitive Neanderthals

they found here and established a race of

“true men”? Could some disaster have destroyed their culture and forced them to build up a new one? Is the Prometheus myth a dim memory of the distant past, ee eee ey ee “oe when Alpha Centauri B lit up the skies? Was the Alpha _ Centauri system the original of the Atlantis myth? No, I don’t think so, but anyone who wants to use it in a

_ science-fiction story is welcome to it. And anyone who wants to start a religious cult based on this notion probably can’t __ be stopped but please—don’t send me any of the literature—

_ and don’t say you read it here first.

And what effect would Sun B (or “Prometheus”) have had ~ on Greek science?

;

Well, in the real world, there was

a time when matters

-

hung in the balance. The popular Greek theory of the universe, as developed by 300 3.c., put the Earth at the center — _ and let everything in the heavens revolve about it, The

F ett of Aristotle’s philosophy was on the side of this — theory. ___ About 280 3.c. Aristarchos of Samos suggested that only _ _ the Moon revolved about the Earth. The planets, including

_Earth itself, he said, revolved about the Sun, thus elaborat-

aia

~

‘ing a ‘heliocentric system. He even had some good notic Poa the relative sizes and distances of the Moon the Sun

side chance ee the great prestige of Aristotle. Howeveen about 150 8.c., Hipparchos of Nicaea worked out the mathe-® ‘matics of the geocentric system so thoroughly that the. competition ended. About 150 a.p. Claudius Ptolemy pui a __ the final touches on the geocentric theory and no one questioned that the Earth was the center of the universe for nearly 1400 years thereafter. But had Prometheus and Vulturius been in the sky, the _Greeks would have had an example of one heavenly bo anyway, that clearly did not revolve primarily about Earth. Vulturius would have revolved about Prometheus, _ __ Aristarchos would undoubtedly have suggested Promethet to be another sun with a planet circling it. The argument by — analogy would, it seems to me, certainly have won out. Copernicus would have been anticipated, B: urthermore, the motions of Vulturius about Prometlicn

would have given a clear indication of the workings of _gravity. The Aristotelian notion that gravity was confined to — Earth alone and that heavenly bodies were immune to # “would not have stood up. ba? Undoubtedly Newton too would have been anticipated by‘fe some two thousand years. E

__ What would have happened next? Would Greek genius

“have decayed anyway? Would the Dark Ages still have — intervened? Or would the world have had a two thousand ~ _year head start in science and would we now be masters of 4

spaceP Or would we possibly be the non-survivors of a nuclear war fought in Roman times? ‘ So that’s how it goes. You start off checking on colt ee shadows in a science-fiction story and end up wondering how different human history might have been (either for good or evil) if only the Sun had had a companion star in

_ its lonely voyage through eternity.

J¢

ee

10

gt

pie

Heaven

8

Ee

a

olay

on Earth

The nicest thing about writing these essays is the constant

mental

exercise

it gives

me.

Unceasingly,

I must

keep my eyes and ears open for anything that will spark _

ee that will, in my opinion, be of interest to the 2 reader. _ For instance, a letter arrived today, asking about the duo-— decimal system, where one counts by twelves rather than by tens, and this set up a mental chain reaction that ended in ~

astronomy and, what’s more, gave me a notion which, as far as I know, is original with me. Here’s how it happened. My first thought was that, after all, the duodecimal system _ is used in odd corners. For instance, we say that 12 objects — make 1 dozen and 12 dozen make 1 gross. However, as far _ as I know, 12 has never been used as the base for a numer oe System, except by mathematicians in pla A number which has, on the othez han:!. been used as na :

base for a formal positional notation is € ' The ancient Bab;- _ lonians used 10 as a base just as we do, but frequently used — 60 as an alternate base. In a number based on 60, what we — call the units column would contain any number from 1 toe: 59, while what we call the tens column would be the “six-

ties” column, and our hundreds column (ten times ten) would _ be the “thirty-six hundred” column (sixty times sixty). Thus, when we write a number, 123, what it really stands | for is (1 x 102) + (2101) + (3 x 10°). And since 102 —

equals 100, 10' equals 10 and 10° equals 1, the total aa

_100 + 20 + 3 or, as aforesaid, 123.

But if the Babylonians wrote the equivalent of 123, usin

60 as the base, it would mean

(1 x 602) + (2 X 60")

ie

ug

3 X 60°). And since 60? equals 3600, 60' equals 60 and —3 30° ee 1, this works out to 3600 + 120 + 3, or 3723 notation. Ustseaspositional notation with

=

120

@

Fact and Fancy

the base 60 is a “sexagesimal notation” from the Latin word -for sixtieth.

~

he

the word “sixtieth” suggests, the sexagesimal notation

As

can be carried into fractions too. Our own decimal notation will allow us to use a figure such

as 0.156, where what is really meant is 0 + 40 + Yoo +

_ 000. The denominators, you see, go up the scale in multiples of

10. In the sexagesimal scale, the denominators

would

go

| “up the scale in multiples of 60 and 0.156 would represent

0 + Y%o + %c00 + %r6.000, since 3600 equals 60 X 60, — 216,000:equals 60 X 60 x 60, and so on.

;Those

of you who know all about exponential notation will . ho doubt be smugly aware that 4o can be written 10, Yoo |

~ €an be written 10-2 and so on, while %o can be written 60%, ~ ~ ¥%eo0 can be written

602

and so on.

Consequently,

a full

_ number expressed in sexagesimal notation would be some-

thing like this: (15) (45) (2).(17) (25) (59), or (15 xX 60?) + (45 X 60") + (2 x 60°) + (17 X 607) + (25 xX 60%) _ + (59 x 60°), and if you want to amuse yourself by ~ ; working out the equivalent-in ordinary decimal notation,

_

please do. As for me, I’m chickening out right now. _ All this would be of purely academic interest, if it weren't _ for the fact that we still utilize sexagesimal notation in at _ least two important ways, which date back to the Greeks. _The Greeks had a tendency to pick up the number 60 from __ the Babylonians as a base, where computations were compli-

cated, since so many numbers go evenly into 60 that fractions.

are avoided as often as possible (and who wouldn't avoid b fractions as often as possible?). ; One theory, for instance, is that the Greeks divided the _ radius of a circle into 60 equal parts so that in dealing with half a radius, or a third, or a fourth, or a fifth, or a sixth,

or a tenth (and so on) they could always express it as a whole number of sixtieths. Then, since in ancient days the value of m (pi) was often set equal to a rough and ready 3, and since the length of the circumference of a circle is equal to twice = times the radius, the length of that circumference is equal to _ 6 times the radius or to 360 sixtieths of a radius. Thus (perhaps) began the custom of dividing a circle into 360 equal parts.

. Another possible reason for doing so rests with the fact . _that the sun completes its circuit of the stars in a little over 365 days, so that in each day it moves about Yes of the way around the sky. Well, the ancients weren’t going to quibble — Re ee ae ee a ee ne ee ae ee ee

’ about a few days here and there and 360-is so much easier

ip»a + uty .

..

cer, “

Heaven on Earth

@

121

—

to work with that they divided the circuit of the sky into _

tag

that many divisions and considered the sun as traveling, — through one of those parts (well, just about) each day. A 360th of a circle is called a “degree” from Latin words meaning “ down.” If the sun is viewed as traveling down a long circular stairway, it takes one step down (well, just about) each day. Each degree, if we stick with the sexagesimal system, can a.

be divided into 60 smaller parts and each of those smaller parts into 60 still smaller parts and so on. The first division was called in Latin pars minuta prima (first small part) and tthe second was called pars minuta secunda (second small tpart), which have been shortened in English to minutes and

—

‘seconds respectively. We

bolize the degree by a little circle (naturally), the

rminute by a single stroke, and the second by a double stroke, _ sso that when we say that the latitude of a particular spot on ¢earth is 39° 17’ 42”, we are saying that its distance from the sequator is 39 degrees plus 1% of a degree plus *%600 of a — (degree, and isn’t that the sexagesimal system? The second place where sexagesimals are stil] used is in. [Measuring time (which was originally based on the moveiments of heavenly bodies). Thus we divide the hour into minutes and seconds and when we speak of a duration of 1_

hour, 44 minutes, and 20 seconds, we are speaking of a dura|tion of 1 hour plus 44% of an hour plus ?%eo0 of an hour. You can carry the system further than the second and, in jthe Middle Ages, rents astronomers often did. There is a ‘record of one who divided one sexagesimal fraction into anjother and carried out the quotient to ten sexagesimal places, which is the equivalent of 17 decimal places. Now let’s take sexagesimal fractions for granted, and let’s consider next the value of breaking up circumferences of circles into a fixed number of pieces. And, in particular, con-

sider the circle of the ecliptic along which the sun, moon, and planets trace their path in the sky. After all, how does one go about measuring a distance along the sky? One can’t very well reach up with a tape measure. Instead the system, essentially, is to draw imaginary lines from the two ends of the distance traversed along the

ecliptic (or along any other circular arc, actually) to the center of the circle, where we can imagine our eye to be, and to measure the angle made by those two lines. ;

gabe value of this system is hard to explain without a dia-

_

Pett

4

aes

¢@

(122

‘-

Fact and Fancy

; ram, but I shall try to do so, with my usual dauntless — bravery (though you're welcome to draw one as I go along, © oe “dust in case I turn out to be hopelessly confusing).

"Suppose you have a circle with a diameter of 115 feet, and.

~ another circle drawn about the same center with a diameter—

of 230 feet, and still another drawn about the same center — with a diameter of 345 feet. (These are “concentric circles”

. _ andwould look like a target.) The circumference of the innermost circle would be about

360 feet, that of the middle one 720 feet and that of the

‘

- outermost 1080 feet. XY - Nowamark off %60 of the innermost circle’s circumference, . length of arc 1 foot long, and from the two ends of the arc — »

draw lines to the center. Since 1460 of the circumference is

| degree, the angle formed at the center may be called 1 legree also (particularly since 360 such arcs will fill the _ entire circumference and 360 such central angles will conse-_

_quently fill the entire space about the center).

If

Rs

the I-degree angle is now extended outwards so that’

the arms cut across the two outer circles, they will subtend 2 2-foot arc of the middle circle and a 3-foot circle of the©

outer one. The arms diverge just enough to match the ex‘panding circumference. The lengths of the are will be

| different, but the fraction of the circle subtended will be | the same. A 1-degree angle with vertex at the center of a_ circle will subtend a 1-degree arc of the circumference of any circle, regardless of its diameter, whether it is the

assume a Euclidean geometry, I quickly add). The same is _ analogously true for an angle of any size, __ Suppose your eye was at the center of a circle that had _ two marks upon it. The two marks are separated by % the

_ circumference of the circle, that is by 36% or 60 degrees of

__ arc. If you imagine a line drawn from the two marks to your. ' eye, the lines will form an angle of 60 degrees. If you look

firstat one mark, then at the other you will have to swivel) yur eyes through an angle of 60 degrees. _ And it wouldn’t matter, you see, whether the circle was a ile from your eye or a trillion miles. If the two marks were of the circumference apart, they would be 60 degrees art, regardless of distance. How nice to use such a meas‘e, then, when you haven't the faintest idea of how far circle is. ealad _away So, the since through most of man’s Bistory ,nstronct dias

ae Do

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Heaven

on Earth

@

123

notion of the distance of the heavenly objects in the sky, agular measure was just the thing. And if you think it isn’t, try making use of linear measure. average person, asked to estimate the diameter of the moon in appearance, almost instinctively makes use of mear measure. He is liable to reply, judiciously, “Oh, about | f foot.” But as soon as he makes use of linear measure, he is setting s specific distance, whether he knows it or not. For an object

i foot across to look as large as the full moon, it would have » be 36 aie away. I doubt that anyone who judges the aoon to be a foot wide will also judge it to be no more aan 36 yards distant. If we stick to angular measure and say that the average

iidth of the full moon is 31’ (minutes), we are making no

adgments as to distance and are safe. But if we're going to insist on using angular measure, tith which the general population is unacquainted, it bepmes necessary to find some way of making it clear to veryone. The most common way of doing this, and to pic-

mre the moon’s size, for instance, is to take some common

rrcle with which we are all acquainted and calculate the Gstance at which it must be held to look as large as the

aoon., One such circle is that of the twenty-five-cent piece. Its dameter is about 0.96 inches and we won't be far off if we pnsider it just an inch in diameter. If a quarter is held 9 eet from the eye, it will subtend an arc of 31 minutes, That aeans it will look just as large as the full moon does, and,

it is held at that distance between your eye and the full a00n, it will just cover it. Now if you've never thought of this, you will undoubtedly surprised that a quarter at 9 feet (which you must imagine rill look quite small) can overlap the full moon (which you ~ robably think of as quite large). To which I can only say: iry the experiment! Well, this sort of thing will do for the sun and the moon ut these, after all, are, of all the heavenly bodies, the largest

1 appearance. In fact, they’re the only ones (barring an occa-

ional comet) that show a visible disc. All other objects are neasured in fractions of a minute or even fractions of a scond, : It is easy enough to continue the principle of comparison saying that a particular planet or-star has the apparent iameter of a quarter held at a distance of a mile or ten

-

4e

Fact and Fancy

miles or a hundred miles and this is, in fact, what is gener-_ : allydone. But of what use is thatP You can’t see a quarter at all, at such distances, and you can’t picture its size. Youre B just substituting one unvisionable measure for another.

“ ‘There must be some better way of doing it.

= And at this point in my thoughts, I had my original (I : hope) idea.

Suppose that the earth were exactly the size it is but "were a huge, hollow, smooth, transparent sphere. And suppose’ you were viewing the skies not from earth’s surface, et but with your eye precisely at earth’s center. You would then see all the Fesieels objects projected onto the sphere of the

—

~ earth.

In effect, it would be as though you were using the entire

globe of the earth as a background on which to paint a - replica of the celestial sphere. The value of this is that the terrestrial globe is the one — 2 sphere upon which we can easily picture angular measurement, since we have all learned about latitude and longitude ©

_ which are angular measurements. On the earth’s surface, 1 _ degree is equal to 69 miles (with minor variations, which we

_ can ignore, because of the fact that the earth is not a per_ fect sphere). Consequently, 1 minute, which is equal to Yo 7 of a degree, is equal to 1.15 miles or to 6060 feet, and 1

second, which is equal to %o of a minute, is equal to 101 4 y feet.

You see, then, that if we know the apparent angular diameter of a heavenly body, we know exactly what its diameter would be if it were drawn on the earth’s surface to scale. The moon, for instance, with an average diameter of 31

minutes by angular measure, would be drawn with a diam‘ __ eter of 36 miles, if painted to scale on the earth’s surface, _ It would neatly cover all of Greater New York or the space

_ between Boston and Worcester. _ Your first impulse may be a “WHAT!” but this is not really 3

__as large as it seems, Remember, you are really viewing this _ scale model from the center of the earth, four thousand

miles

?

from the

surface,

and

just ask yourself

how

large

_ Greater New York would seem, seen from a distance of 4000

__miles. Or look at a globe of the earth, if you have one and ; _ picture a circle with a diameter stretching from Boston to. ay

_ Worcester and you will see that it is small indeed compared > Pat a to the whole surface of the earth, just as the moon itself is=.£: __

_small indeed compared to the whole surface of the sky e ah

Heaven on Earth

@

125

(Actually, it would take the area of 490,000 bodies the size of the moon to fill the entire sky, and 490,000 bodies the

size of our painted moon to fill all of the earth’s surface. ) But at least this shows the magnifying effect of the device I am proposing, and it comes in particularly handy where bodies smaller in appearance than the sun or the moon are concerned, just at the point where the quarter-at-a-distanceof-so-many-miles notion breaks down. For instance, in Table 1, I present the maximum an diameters of the various planets as seen at the time of their closest approach to earth, together with their linear diameter to scale if drawn on earth’s surface. I omit Pluto because its angular diameter is not well known.

However,

if we assume

that planet to be about the

size of Mars, then at its furthest point in its orbit, it will still have an angular diameter of 0.2 seconds and can be presented as a circle 20 feet in diameter. TABLE

Planet

1

Planets to Scale

Angular diameter (SECONDS)

Linear diameter (FEET)

Mercury Venus Mars Jupiter Saturn Uranus

12.7 64.5 25.1 50.0 20.6 4.2

1280 6510 2540 5050 » 2080 425

Neptune

2.4

240

}

Each planet could have its satellites drawn to scale with great convenience. For instance, the four large satellites of Jupiter would be circles ranging from 110 to 185 feet in

diameter, set at distances of 3 to 14 miles from Jupiter. The entire Jovian system to the orbit of its outermost satellite - (Jupiter IX, a circle about 5 inches in diameter) cover a circle about 350 miles in diameter.

would

The real interest in such a setup, however, would be the stars. The stars, like the planets, do not have a visible disc

r topve eyes. Unlike the planets, however, they do not have a

ible Seay even toHe largest oe. Ps

The aes oe

— .

re

26 e

Fact and Fancy

b at Pluto) can be blown up to discs even by moderate-sized

telescopes; not so the stars. i By indirect methods the apparent angular diameter of ome stars has been determined. For instance, the largest gular diameter of any star is probably that of Betelgeuse,

vhich is 0.047 seconds. Even the huge 200-inch telescope — nnot magnify that diameter more than a thousandfold, and der such magnification the largest star is still less than 1 ute of arc in appearance and is therefore no more of a disc to the 200-incher than Jupiter is to the unaided eye. ~ And of course, most stars are far smaller in appearance than

giant Betelgeuse. (Even stars that are in actuality larger than Betelgeuse are so far away as to appear smaller.) — - But on my earth scale, Betelgeuse with an’ apparent diam-

eter of 0.047 seconds of arc would be represented by a circle about 4.7 feet in diameter. (Compare that with the 20 feet of even distantest Pluto.) __ However, it’s no use trying to get actual figures on angular diameters because these have been measured for very _ few stars. Instead, let’s make the assumption that all the ‘stars have the same intrinsic brightness the sun has. (This is not so, of course, but the sun is an average star, and sothe assumption won't radically change the appearance of the

_ .

_ universe. ) s Now then, area for area, the sun (or any star) remains at

_constant brightness to the eye regardless of distance. If the

‘Sun were moved out to twice its present distance, its apparent brightness would decrease by four times but so would ° “itsapparent surface area. What we could see of its area | would be just as bright as it ever was; there would be less —

"of it, that’s all.

|

_ The same is true the other way, too. Mercury, at its closest

_approach to the sun, sees a sun that is no brighter per square _ second than ours is, but it sees one with ten times as many —

Square seconds as ours has, so that Mercury’s sun is ten _ times as bright as ours. Well, then, if all the stars were as luminous as the sun, _then the apparent area would be directly proportional to the apparent brightness. We know the magnitude of the sun _ (—26.72) as well as the magnitudes of the various stars, and _ that gives us our scale of comparative brightness, from

which we can work out a scale of comparative areas and, therefore,

comparative

diameters.

Furthermore,

since

—

we

know the angular measure of the sun, we can use the com- i

parative diameters ee

to calculate the comparative angular — na

e

hae

oe

‘

st

i.

we

Se

Heaven on Earth

ne

|

se

@

127 ia

which, of course, we can convert to linear diam-

ts (to scale) on the earth.

But never mind the details (you’ve probably skipped the

hey paragraph already), I'll give you the results in ple 2. "The fact that Betelgeuse has an apparent diameter of ‘47 and yet is no brighter than Altair is due to the fact Et Betelgeuse, a red giant, has a lower temperature than » sun and is much dimmer per unit area in consequence. member that Table 2 is based on the assumption that all irs are as luminous as the sun.) So you see what happens once we leave the Solar System. tithin that system, we have bodies that must be drawn to lle in yards and miles. Outside the system, we deal with idies which, to scale, range in mere inches, 2 TABLE 2 _ Stars to Scale . Angular diameter ugnitude of star

1 0 ll 2 3 4 D iD

(e.g. (e.g. (e.g. (e.g.

Linear diameter

(SECONDS)

Sirius) Rigel) Altair) Polaris)

0.014 0.0086 0.0055 0.0035 0.0022 0.0014 0.00086 0.00055

(INCHES)

17.0 10.5 6.7 4.25 2.67 1.70 1.05 0.67

If you imagine such small patches of earth’s surface, as en from the earth’s center, I think you will get a new ion as to how small the stars are in appearance and why =scopes cannot make visible discs of them. The total. number of stars visible to the naked eye is about 30, of which two thirds are dim stars of 5th and 6th magude. We might then picture the earth as spotted with JO stars, most of them being about an inch in diameter. ere would be only a very occasional larger one; only 20, told, that would be as much as 6 inches in diameter.

The average distance between two stars on earth’s surface

‘uld be 180 miles. There would be one or, at most, two ts in New York State, and one hundred stars, more or

8,

within the territory of the United States eS.

as x

(including

;

a

128

©

Fact and Fancy

The sky, you see, is quite uncrowded, regardless of its appearance. ~ Of course, these are only the visible stars. Through a _

telescope, myriads of stars too faint to be seen by the naked eye can be made out and the 200-inch telescope cam

photograph stars as dim as the 22nd magnitude. A star of magnitude 22, drawn on the earth to scale, would

be a mere 0.0004 inches in diameter, or about the size of a

bacterium.

_

. ~

(Seeing a shining bacterium on earth’s surface

from a vantage point at earth’s center, 4000 miles down, is a

amatic indication of the power of the modern telescope.) The number of individual stars visible down to this magnitude would be roughly two billion. (There are, of course, at least a hundred billion stars in our Galaxy, but almost all . of them are located in the Galactic nucleus which is com: ‘pletely hidden from our sight by dust clouds. The twe billion-we do see are just the scattering in our own neighbor: hood of the spiral arms.) Drawn to scale on the earth, this means that among the 6000 circles we have already drawn (mostly an inch if diameter) we must place a powdering of two billion more

dots, a small proportion of which are still large enough t see, but most of which are microscopic in size.

The average distance between stars even after this mighty powdering would still be, on the earth-scale, 1700 feet. This answers a question I, for one, have asked myself i

the past. Once a person looks at a photograph showing the myriad stars visible to a large telescope, he can’t help won: dering how it is possible to see beyond all that talcur powder and observe the outer galaxies. Well, you see, despite the vast numbers of stars, the cleat

space between them is still comparatively huge. In fact, i has been estimated that all the starlight that reaches us i equivalent to the light of 1100 stars of magnitude

1. Thi

means that if all the stars that can be seen were massed to

_ gether, they would fill a circle (on earth-scale) that woul be 18.5 feet in diameter. From this we can conclude that all the stars combined ad

not cover up as much of the sky as the planet Pluto. As :

matter of fact, the moon,

all by itself, obscures nearly 30

times as much of the sky as do all other nighttime heavenh

bodies, planets, satellites, planetoids, stars, put together. Rt:

There would be no trouble whatever in viewing the space

outside our Galaxy if it weren’t for the dust clouds. Thos

y ‘the onlySree and: they can’t be removed ey

set up a telescopein space. What a pity the universe couldn’t really be projectec rth’speer temporarily—just long enough to send out tl ’s seven maids with seven mops with strict orders universe a thorough dusting. | "Howhappy astronomers would then bel

:

11 Our Lonely Planet

One of the questions that is asked innumerable times these daring days (I have even asked it myself) is: “If - there is life elsewhere in the’ Universe, why hasn't it reached

us?” Since modern views of the Universe would have it that solar systems are the rule rather than the very rare exception” we thought they were twenty years ago, there should be millions, perhaps billions, of Sek with physical and chemical characteristics reasonably close to those of Earth in our own Galaxy alone. Since modern views on biochemis-_

try would seem to make the origin of life the inevitable con-" sequence of Earthlike physics and chemistry rather than a

rare and miraculous occurrence, there should also be millions, °

Realy billions, of independent life-systems in our Galaxy

one. Since most other planets are probably as old as our own, there has been ample time for evolution elsewhere as well as here. Suppose that one system of planetary life out of a thousand develops organisms with sufficient intelligence to understand and control the forces of Nature. Then there are still thousands, perhaps millions, of intelligent life-forms in our own Galaxy alone.

Now, to repeat: “If there is life elsewhere in the Universe, why hasn’t it reached us?”

Well, through a circuitous line of reasoning, I think I have a possible answer that sounds well to me. The line of reasoning starts in the Bible,

In Genesis 15:5, it is related that the Lord encouraged the

patriarch Abram, who feared that, since he was childless, ear-

lier promises that he would be made “a great nation” would

not, after all, be kept. The verse reads: “And he [the Lord].

4

Our Lonely Planet

@

131 th,

rought him forth abroad and said, Look now toward eaven, and tell the stars, if thou be able to number them: he said unto him, So shall thy seed be.”

— | cre

This is an example of the typical way in which the an- —

tients expressed large numbers: “as the stars in the heaven” — r “as the sand grains of the shore” or “as the water drops of _

e ocean.” ; Now there are many drops of water in the ocean and y grains of sand in the sea shore. As ‘ar as ancient man

concerned, such numbers were finite. Except for occa- Vr

tional geniuses like Archimedes, times could even consider that pnough to express sand grains and A.D. before the word “million” was

no man before modern umbers might exist great water drops. (It was 1300 invented. Until then, the

sargest number word was “myriad,” which was Greek for

0,000. Even Archimedes, in calculating the number of ooppy seeds in the entire Universe as he knew it, used ex-

_

oressions meaning “myriads of myriads of myriads. . . .”) But what about the number of stars in the sky? Are they bean’ as innumerable as the sand grains and water drops? _ To be sure, if the Lord had chosen to reveal to Abram all. che stars in the Universe in one flash of miraculous sight, — Abram would have seen a minimum of 10,000,000,000,000,- _ 0,000,000 (ten billion trillion) stars, and that would cerainly have been innumerable to him, fa However,

no Biblical commentator

I’ve ever heard of has

suggested that this was what happened. The suggestion of vast numbers in Genesis 15:5 is always taken as applying 0 only those stars actually visible in the sky to the naked aye. Even

with that limitation, most people, I'm sure, would

onsider the metaphor quite an effective one and not in the east ridiculous. I can see why they should think that, too. I myself ama ‘ity boy and I’ve hardly ever really seen the stars, The

uildings block them

out; the street lights dim them

~

out;

moke and dirt blot them out. And only once did I get a real hance to find out what I was missing. I spent the night at a friend’s country house in New fampshire, you see, and when night came, I couldn't sleep.

t got dark, it seems. Battling my ess I had never really ed

_

primitive fears of a darkI thought I would step

into the open and prove to myself that there was noth-

0 be afraid of. It was a warm summer night, so I just d outside in my pajamas and slippers. a

_

igs CE

Te Mite,

132

¢

Fact and Fancy

There was no Moon, no clouds, no artificial light for miles

around. So for the first time in my life, I saw the starsl—|

millions of them, billions of them, trillions of them.

|

_ It was a wonderful sight. I stayed out, staring, for a long "time, and to the day I die I shall always remember that once I saw the stars.

But the question is, how many stars did I really see?

The faintest star that can be seen with the naked eye, under the best conditions, is of magnitude 6.5 and the num_- ber of stars that exist in the entire circuit of the skies that

bright or brighter is just about 6000. That’s all. That’s the hard fact of it. Six thousand. And since at any moment only half the sky is above the horizon,

the number

of stars

theoretically

visible

at any

one moment is 3000. But then the atmosphere absorbs some of the light that passes through it. Even the purest, clearest atmosphere ASrciie 30 per cent of the starlight that strikes it. As you tur your gaze toward the horizon, you are looking through a much greater thickness of air than you do when you stare up at zenith. The result is that the faintest stars which can be just made out near the zenith are lost to vision if they are located lower in the sky. ; Actually, then, the total number of stars I could possibly

have seen outside my friend’s summer house (even countin those obscured by trees and unevenness of the horizo 5 ~ was 2500.

:

The stars in the sky innumerable? Hah. Even the Babylonian shepherds could have counted to 2500, I’m sure. One dramatic way of pointing out the difference between the facts as they are and the facts as we think they are is to

pose the following riddle: If, at any particular time, the

Moon were removed from the sky, how many stars (visible

ones, of course) would it have been covering?

If one thinks of the size of the Moon and the thickness

.

with which stars are strewn across the vault of the night

sky and then follows intuition, the answer given might be five or seven or ten or fifty.

Anyway, quite a few. What’s your guess? ; But let’s not go by intuition. The circuit of the skies is

measured by degrees—360 degrees for the full circumference. The area of the total sky (or of any sphere, for that matter) works out to about 41,200 square degrees. Since there a

Our Lonely Planet

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133

(6000 visible stars all told, we can say that there is one star

: for every 6.9 square degrees of sky. But the apparent diameter of the Moon’s sphere is (on the average) 0.52 degrees. Its area is therefore 0.21 square degrees and the odds are thus about 33 to 1 that the removal of the Moon would reveal not one star behind it. This stars-in-the-sky situation changes at once if we view

‘the skies from the Moon, or from a space station, or from

any point outside a planetary atmosphere. Science-fiction writers usually talk about the “familiar constellations” seen from other worlds in our Solar System. Yet the notion is almost certainly wrong. The reasoning behind the “familiar constellations” busi- — ness is that any change of position within the Solar System involves so small a movement in comparison with the distances of the stars that there would be no noticeable alteration in their relative positions. And that’s right, as far as it goes. However, remember the 30 per cent of starlight that is absorbed by our atmosphere. On the Moon, to use that as an’ example, no starlight is absorbed and every individual star seems 1% times as bright as it does to us on Earth. Another way of putting it is that every star is 0.4 lower (i.e. brighter) in magnitude on the Moon than on the Earth. _ This is a noticeable increase in brightness but not an overwhelming one. The eye would grow accustomed to it quickly and, if that were

all, the Moon’s

starry sky would

seem

gaudy (with its brighter and non-twinkling stars) but not strange.

But it’s not all. Allow for this uniform increase of 0.4 magnitude and the limit of naked-eye visibility stretches down to stars of magnitude 6.9. That is, a star which is of — magnitude 6.9 on Earth (and therefore invisible to the naked Bat isof magnitude 6.5 as seen from the Moon and just.

visible. So what? So this: The number of stars increases very rapidly with magnitude. Any glance at the sky will convince you that there are many more dim stars than bright stars. To be bright, a star has to be big or close. Well, there are more small stars than big ones and since volume increases as the cube of the radius, there is more room far away than close by. In general, the number of stars at each level of magnitude is three times the number at the previous level. Thus

there are about 350 stars between magnitudes 3 and 4,

_

134 @ .

Fact and Fancy

%.

r

?

about 1100 between magnitudes 4 and 5, and about 3200 between magnitudes 5 and 6.

sa

In the interval between 6.5 and 6.9 there are 6000 stars. — Allof these are not visible on Earth and are visible on the Moon, just because the Moon lacks an atmosphere: The night —

4 sky as seen from the Moon, therefore contains 12,000 stars, —

- twice the number that can be seen from Earth. Furthermore | the number that can be seen above the horizon at any one time is not lessened by the effect of additional atmospheric absorption. The actual number seen at any one time from —

levél ground on the Moon is therefore 2% times the number — seen under similar conditions on Earth.

_ From the Moon (or in space, generally) you could still —

make out patterns of bright stars such as those of the Big —

Dipper or of Orion, but the finer details would all be drowned out in thousands of additional stars, and the over-all

_ effect would be that of a completely strange sky.

.

In other words, when we leave Earth we say farewell to our dear “familiar constellations.” oy

This raises another point. Are there places in the Universe — where the starry sky is even more impressive than it appears — _ from the Moon? . ___ Obviously, it would be more impressive to inhabitants who | _ lived on a planet revolving about a Sun that was part of ©

__ the densely populated central nucleus of a Galaxy or within — _a globular cluster. Our own Sun, after all, is way out in the 7 _ Sparsely-populated spiral arm of our Galaxy.

AY

In

our home neighborhood there are 188 stars or star

_ systems

(that is, binaries

or multiple

stars) known

to be_

_ located within 10 parsecs of Earth. (A parsec is equal to _ 3.26 light-years). This means that, on the average, there are

4% stars (or star systems) per 100 cubic parsecs of space

__and that the average distance between stars (or star systems) in our neck of the woods is about 2.8 parsecs, which is equivalent to 9.2 light-years.

_

_At the Galactic center or in a globular cluster (a positive

__ photograph of which, under high magnification, looks for all __ the world like a heap of talcum powder) the average dis-

_ tance between stars is one light-year. A hundred cubic par-

sec volumes in which stars were this closely packed would

contain not 4% stars but 3500 stars. ; ; In other words, all things being otherwise equal, the number of stars visible in the skies near the Galactic center

uld be 780 times as many as those visible out here. Even=. *

PR

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PUD

Palle ©

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bea

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Our Lonely Planet

@ilowing for horizon effects, the number

@

135

of stars visible

above the horizon would be about 2,000,000. There would be, on the average, 100 visible stars per

quare degree of the sky and a globe the area of the Moon ould be covering 20 stars, on the average. There would naturally be more stars at every level of ightness. The skies in the Galactic center would contain ore first magnitude stars (about 7500) than our heavens. mtain of stars of any description. Furthermore, the chances are very much in favor of there ibeing a number of stars brighter than any of those in our sown skies. We can duplicate Galactic center conditions by timagining all the visible stars we see pulled in to %2 of ttheir actual distance. Any star whose nearness is increased 99.2 times has its brightness increased 9.2 X 9.2 or 85 times. ‘A brightness increase of 85 is equivalent to a decrease in magnitude of 4.8, Sirius, in other words, instead of the magnitude of —1.6 ‘which it now has, would burn with a brightness equal to a magnitude of —6.4. It would be eight times as bright as ‘Venus at its brightest. Ten other stars in our sky would

become brighter than Venus under these conditions and about 250 stars altogether would be brighter than Sirius (our brightest star) appears to us now. The starlight in such a sky would by no means be negligible. It would be roughly equal to the light of the full

Moon as seen from Earth, so that a cloudless night, under such conditions, would never be dark,

Despite all this gorgeous display, the stars would stil] all Took like stars. The chances of having any stars close enough to look like tiny suns with visible globes is just about nil. Assuming our Sun to be an average star and placing it at a light-year’s distance (the average interstellar distance at the Galactic center), its apparent diameter would be about 0.03 seconds of arc. (There are 60 seconds to 1 minute and 60 minutes to 1 degree.) In order for a heavenly body to be

Seen as a globe it must have an apparent diameter of at least 3 minutes. Even the 200-inch Palomar telescope would’ not show the Sun to be a tiny globe at a distance of a lightyear. Of course, one light-year is only the average distance be-

tween stars. Some stars would be closer to one another. Well,

in order for a star the size of the Sun to be seen as a globe it would have to be distant not more than a billion miles, SO

gle

aeAE

a)

aie

Uranus. It is quite impossible for a star to be that close 10

another unless it is part of a binary, and I'm not considering _

— _that situation here. But then again, suppose the star to be larger than the _~ Sun. All right. In order for a star to be seen as a globe at a -distance of a light-year, it would have to have a diameter of ~ about 8000 times that of the Sun. If such a star were in the

position of our Sun, it would fill up the Solar System beyond the orbit of Neptune. Stars that size are freaks indeed and the chances of finding one within a light-year of your planet: e virtually nil. .

_. Now what does all this have to do with the neglect of our

own world by the possible intelligences elsewhere in our

__ Galaxy? Consider several points:

“1.

About

-

90 per cent of the stars and hence, assuming

_ random. distribution, about 90 per cent of the intelligences” _ which have evolved, exist in the crowded Galactic center. * ‘ 2. A closer spacing of stars makes interstellar travel some-

. what less of a

problem while the concomitantly greater “star-

_.riness” of the aryis liable to make interstellar travel more of

a popular goal and dream. » _ 3. The intermingling of cultures is a catalyst for advanceMent.

;

the

_ _ Now then, if all intelligences have an equal chance of being

of

the first to. attain interstellar travel, then on the basis

point 1, it is nine times as likely that the victory be

_ attained first somewhere in the Galactic center.

-_

=

If the chances are not equal but are inversely proportional _

to the average distance separating the stars, then, combining —

points 1 and attained first __. Once one ences that --colonialized,

2, it is eighty times as likely that the victory be in the Galactic center. , group achieves interstellar travel, other intelliare reached by it will either be wiped out or or will also learn

the trick and proceed

to

spread it to those intelligences they can reach. Therefore _ what I mean by point 3 is that although it might take six billion years for one world to develop a life-form that can, in turn, needs interstellar travel; it will then perhaps take as little as a thousand years for all the intelligences within reach to develop it also. cee, In short, then, if even one group of intelligences has

y

+uy

i.

Our Lonely Planet

@

1;

kind of Galactic federation already exists. (Perhaps there a1

some small independent federations, each not knowing of tl

other’s existence, among the various globular clusters.) But then why hasn’t the federation contacted us? Easy. I used the phrase “intelligences within reach” a fe lines back and that’s the key point. Consider the economics of the thing. With 90 per cent « the worlds, of the resources, of the intelligences in the Gala

tic center, why bother venturing out into the spiral arm where distances that must be covered between stars are nin times as great and the pickings in terms of worlds, of re sources, of intelligences is only one tenth as great? When a sample of iron ore is too low in iron, it become

unprofitable to work it. And when a sample of space become too thin in worlds, is it too unprofitable to enter it?

~

If so, here we are on our lonely planet, a bunch of hick

way

out in the sticks, lost in the backwoods where no reasor

able beings would waste the energy to go. And if so, that the way we're likely to stay, too, unless we find methods spanning interstellar distances ourselves, go down to th _ Big Town we call the Galactic center and force ourselves o: the city slickers. Maybe we'll do just that someday-—if all this is so. But is all this soP More particularly, is it true that mer distance need be such a barrier. It’s a natural tendency t consider the light-speed limit absolute and to think of inter stellar travel as involving years, centuries, millennia, anc not to think of intergalactic travel at all. Yet must we thinl in this manner? Down to 1800 we knew of no way in which a man coulc move more quickly than a horse’s straining muscles could carry him, or than a gale could force a ship through water. It didn’t prevent the imaginative fiction writers of those days from thinking up devices such as flying horses, flying carpets, seven-league boots, and obliging atone None of that ever came to pass; it was all gibberish. But locomotives, autos, planes, and jets came to pass and, really, those did the trick more efficiently, more reliably, or both. The imaginative fiction writers of these days try to get around the light-speed limit by thinking up devices such as hyperspace, inertia-less drive and so on. That is just gibberish, too, and perhaps as unlikely as flying carpets. Nevertheless, the real equivalent may someday exist and distance may

become quite unimportant as a barrier. (On the surface of ys

at a3

4

ae At

ca ‘a

=

of

ss

=

Phose Crazy Ideas

They must permit him to create. They

m

‘ oy

1 him

to

go ahead ube a crackpot.? | fame ch How is this permission to be granted? Can four essenally non-creative people find it within themselves to gran : h permission? Can the one creative person find it witl mself to accept it? ee I don't know. Here, it seems to me, is where we need ex-

perimentation and perhaps a kind of creative breakthrough pout creativity. Once we learn enough about the whole mat-— sr, who knows—I may even find out where I get those crazy

wy

Always with the provision of course, that the crackpot creathat results survives the test of hard inspection. Though many — > products of genius seem crackpot at first, very few of the — ns that seem crackpot turn out, after all, to be products of

al

go-into that aspect of thematterin the next —

RS)

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16

My Built-in Doubter

: " Once I delivered myself of an oration befo a small but select audience of non-scientists on the t

_ of “What Is Science?” telligently.

speaking seriously and, I |

‘ Having completed the talk, there came the question perio and, bless my heart, I wasn’t disappointed. A charming you

lady up front waved a pretty little hand at me and aske

- not a serious question on the nature of science, but:‘ _ Asimov, do you believe in flying saucers?” _ With a fixed smile on my face, I proceeded to give os answer I have carefully given after every lecture I have i livered. I said, “No, miss, I do not, and I think anyone does is a crackpot!”* % And oh, the surprise on her facel f

_ It is taken for. granted° by : everyone, : it seems . to me, °

because I sometimes write science fiction, I believe in flyi saucers, in Atlantis, in clairvoyance and levitation, in tk

prophecies of the Great Pyramid, in astrology, in Fort’s theo _ries, and in the suggestion that Bacon wrote Shakespeare. ___No one would ever think that someone who writes fan asies for pre-school children really thinks that rabbits car alk, or that a writer of hard-boiled

detective

stories really

thinks a man can down two quarts of whiskey in five minutes _ then make love to two girls in the next five, or that a write

* Since this article first appeared, I have received strong ob ctions to the use of the word from flying-saucer fanciers. Let mi tr

eh

-

My Built-in Doubter

fa

©

185

or the ladies’ magazines really thinks that virtue always — umphs and that the secretary always marries the handsome ss—but a science-fiction writer apparently must believe in

agg

ing saucers.

Well, I do not. To be sure, I wrote a story

co once about flying

saucers

in

~

which I explained their aehenes very logically. falso wrotsth a Story once in which levitation played a part. e I can buddy up to such notions long enough to write ber, reasonable stories about them, why, then, do I reject

em so definitely in real life? I can explain by way of a story. A good friend of mine © ice spent quite a long time trying to persuade me of the th and validity of what I considered a piece of pseudolence and bad pseudo-science at that. I sat there listening e stonily, and none of the cited evidence and instances —

id proofs had the slightest effect on me.

if

Finally the gentleman said to me, with considerable anvance, “Damn

it, Isaac, the trouble with you is that you

ve a built-in doubter.”

‘0 which the only answer I could see my way to making as a heartfelt, “Thank God.” un




a,

190

-

7

©

a

—

6

=

ae

Pe |

s

Fact and Fancy

the circles-within-circles jazz. Instead, he had the various”

planets traveling about the sun in ellipses, with the sun at

one focus of the ellipse. It was Kepler’s system that was Cons

rect and, in fact, Kepler’s system has not been changed in” all the time that has elapsed since. Why, then, did Galileo | | é ignore it completely? owas it sa ae had not yet devised it? No, indestiia Kepler’s views on that matter were published in 1609, twen=_ y ; oe ty-seven years before Galileo’s book. Was it that Galileo had happened not to hear of it? Non-— sense. Galileo and Kepler were in steady correspondence and’

were friends. When Galileo built some spare telescopes, he

sent one to Kepler. When Kepler had ideas, he wrote about | them to Galileo. &

The trouble was that Kepler was still bound up with the mystical notions of the Middle Ages. He cast horoscopes for

famous men, for a fee, and worked

seriously and hard on

astrology. He also spent time working out the exact notes: formed by the various planets in creating the “music of the spheres” and pointed out that Earth’s notes were mi, fa, standing for misery, famine, and misery. He also devised

theory accounting for the relative distances of the planets from the Sun by nesting the five regular solids one within

a

another and making deductions therefrom.

Galileo, who must have heard of all this, and who had

nothing of the mystic about himself, could only conclude that Kepler, though a nice guy and a bright fellow and a pleasant correspondent, was a complete nut. I am sure that

Galileo heard all about the elliptical orbits and, considering” =

the source, shrugged it off.

. Well, Kepler was indeed a nut, but he happened to

be

‘luminously right on occasion, too, and Galileo, of all people, couldn't pick the diamond out from among the pebbles.

Shall we sneer at Galileo for that?

Or should we rather be thankful that Galileo didn’t inter=

est himself in the ellipses and in astrology and in the nesting of regular solids and in the music of the spheres. Might”

not credulity have led him into wasting his talents, to the great loss of all succeeding generations? No, no, until some

supernatural force comes

“ to our aid

and tells men what is right and what wrong, men must blun-

der along as best they can, and only the built-in doubter of

the trained scientist can offer a refuge of safety. The very mechanism of scientific procedure,

built

Slowly over.the years, is designed to encourage doubt a

. im

s

My Built-in Doubter

@

191

10 place obstacles in the way of new ideas. No person re- _ peives credit for a new idea unless he publishes it for all ihe world to see and criticize. It is further considered adfisable to announce ideas in papers read to colleagues at public gatherings that they might blast the speaker down jace to face. | Even after announcement or publication, no observation ran be accepted until it has been confirmed by an indepenent observer, and no theory is considered more than, at dest, an interesting speculation until it is backed by experimental evidence that has been independently confirmed and that has withstood the rigid doubts of others in the field, All this is nothing more than the setting up of a system bf “natural selection” designed to winnow the fit from the nimfit in the realm of ideas, in manner

analogous to the con-

wept of Darwinian evolution. The process may be painful pnd tedious, as evolution itself is; but in the long run it gets

results, as evolution itself does. What’s more, I don’t see that

there can be any substitute.

Now let me make a second point. The intensity to which the built-in doubter is activated is also governed by the exBent to which a new observation fits into the organized Structure of science. If it fits well, doubt can be small; if it

its poorly, doubt can be intensive; if it threatens to over-

rum.

the structure

completely,

doubt

is, and

should

be,

nearly insuperable. ‘The reason for this is that now, three hundred fifty years hfter Galileo founded experimental science, the structure that

das been reared, bit by bit, by a dozen generations of sciientists is so firm that its complete overturning has reached the vanishing point of unlikelihood. Nor need you point to relativity as an example of a revoution that overturned science. Einstein did not overturn the structure, he merely extended, elaborated, and improved it. ‘Hinstein did not prove Newton wrong, but merely incomplete. Einstein’s world system contains Newton’s as a special ase and one which works if the volume of space considered ‘not too large and if velocities involved are not too great. “In fact, I should say that since Kepler's time in astronomy,

isince

Galileo’s

time

in physics,

since

Lavoisier’s

time

in

hemistry, and since Darwin’s time in biology no discovery t theory, however revolutionary it has seemed, has actually

med the structure of science or any major branch of

structure has merely been improved and refined.

=

“-.

get

5

ee

192

@

Fact and Fancy

i

ia.

a

The effect is similar to the paving of a road, and its brown

ening and the addition of clover-leaf intersections, and thé installation of radar to combat speeding. None of this, please

notice, is the equivalent of abandoning the road and building another in a completely new direction.

But let’s consider a few concrete examples drawn ‘contemporary life. A team of Columbia University geolo have been exploring the configuration of the ocean botto: for years. Now they find that the mid-Atlantic ridge (a chain of mountains; running down the length of the Atlantic) a rift in the center, a deep chasm or crack. What’s more, this rift circles around Africa, sends an offshoot up into the In-

* dian.Ocean and:across eastern Africa, and heads up the Pa-

cific, skimming the California coast as it does so. It is like _a big crack encircling the earth. ™ The observation itself can be accepted. Those involved were trained.and experienced specialists and confirmation is ample. _ But why the rift? Recently one of the geologists, Bruce

Heezen, suggested that the crack may be due to the expan=

sion of the earth.

=

This is certainly one possibility. If the interior were slowly expanding, the thin crust would give and crack like an eggshell. a But why should Earth’s interior expand? To do so it would have to take up a looser arrangement, become less dense; the atoms would have to spread out a bit.

+"

__.Heezen suggests that one way in which all this might happen is that the gravitational force of the Earth was very slowly weakening with time. The central pressures would

_ therefore ease up and the compressed atoms of the interiot

would slowly spread out. ; But why should Earth’s gravity decrease, unless the force of gravitation everywhere were slowly decreasing with time! Now this deserves a lot of doubt, because there is nothing

in the structure of science to suggest that the force of gravi tation

must

decrease

with time.

However,

it is also true

that there is nothing in the structure of science to sugges that the force of gravitation might not decrease with time. ~ 1As a matter of fact, there have been cosmological speculation: _ (though not, in my opinion, very convincing ones) which involv

' .a steady and very slow decrease.in the gravitational constant; am _ there is also Kapp’s theory, which I described earlier in the book

_ which involves decreasing gravitational force on eazth, withou . involving the gravitational constant, Gee

"7

5 «

he

‘

a

y

-

—® &

hae

re.

|

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=

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My Built-in Doubter

Soe @

™ 193,

Or take another case. I have recently seen a news clipPing concerning an eighth-grader in South Carolina who grew four sets of bean plants under glass jars. One set remained there always, subjected to silence. The other three fihad their jars removed one hour a day in order that they might be exposed to noise; in one case to jazz, in another htc serious music, and in a third to the raucous noises of psports-car engines. The only set of plants that grew vigor-

Ope a

those exposed to the engine noises.

headline

was:

BEANS

CAN

HEAR—AND

MPREFER AUTO RACING NOISE TO MUSIC.

j

THEY

_ Automatically, my built-in doubter moves into high gear.

Jan it be possible that the newspaper story is a hoax? This. $not impossible. The history of newspaper hoaxes is such that one could be easily convinced that nothing in any newsaper can possibly be believed. _ But let’s assume the story is accurate. The next question @to ask is whether the youngster knew what he was doing? Was he experienced enough to make the nature of the noise. ithe only variable? Was there a difference in the soil or in

ithe water supply or in some small matter, which he disrergarded through inexperience?

es inally, even if the validity of the experiment is accepted, what does it really prove? To the headline writer and unidoubtedly to almost everybody who reads the article, it will

prove that plants can hear; and that they have preferences _ and will refuse to grow if they feel lonely and neglected.

This is so far against the current structure of science that ay built-in doubter clicks it right off and stamps it: IGNORE.

‘Now what is an alternative explanation that fits in reasonably ‘well with the structure of science? Sound is not just some-

Ithing to hear; it is a form of vibration. Can it be that sound

ivibrations stir up tiny soil particles making it easier for plants (to absorb water, or putting more ions within reach by impro ing diffusion? May the natural noise that surrounds

plants act in this fashion to promote growth? And may the

jengine noises have worked best on a one-hour-per-day basis

because they were the loudest and produced the most ration? . Any scientist (or eighth-grader) who feels called on to exeriment further, ought to try vibrations that do not ghee ; audible sound; ultrasonic vibrations, mechanical vibrations”

id so on. Or he might also try to expose the plant itself to _

ibrations

of all sorts while leaving the soil insulated; and Ee oo pit

et

@

194

Fact and Fancy

Which finally brings me to flying saucers and spiritualism and the like. The questions I ask myself are: What is the na= ture of the authorities promulgating these and other viewpoints of this sort? and How well do such observations and theories fit in with the established structure of scienceP My answers are, respectively, Very poor and Very poorly, Which leaves me completely unrepentant as far as my double role in life is concerned. If I get a good idea involying flying saucers and am in the mood to write some science

fiction, I will gladly and with delight write a flying-saucer story.

ss

“And I will continue to disbelieve in them firmly in real; . * 4 And if that be schizophrenia, make the most of it.

i.

Pe a e e en a

a bal

17

Battle of the Eggheads

After the Soviet Union placed Sputnik I into orbit on October 4, 1957, the egghead (to use a term invented. vy a blockhead) gained a sudden, unaccustomed respect here ~ n the United States. Suddenly everyone was viewing Ameri- | Lean anti-intellectualism with wild alarm.

It has therefore always tickled my vanity that I wrote an rticle deploring anti-intellectualism in America a year and a half before Sputnik.!

In

it, I disapproved vehemently of those factors in Ameri-

n culture which seemed to me to be equating lack of edu-_ ation with virtue and to be making it difficult for young people to reveal intelligence without finding themselves penalized for it. i. said all this without

mentioning

missiles

or satellites,

ithout any talk of a “scientific race” with any nation. In ct,

I never mentioned

the Soviet Union at all. As I said,

S was one and a half years before Sputnik I, and before flood of Monday-morning

quarterbacks,

wise

after the

vent, that followed hard upon Sputnik I’s launching. _ Of course, I must hastily disavow any intention of trying to imply that I’m smarter or more prescient than the next ow. I did not foresee Sputnik I. An astronomer I know rned me in the spring of 1957 that the Soviet Union might

;

us to the punch and I laughed heartily and confidently. ver, Isaid. _

only means I never thought intelligence was im-

ause we had to keep ahead of the Soviet ence was important for various other

—

Re

See ee

EO

a

Te

Oe

he

ee

es

een

ee ee

ee

.

Fact and Fancy

as 196 @

» good and sufficient reasons, and sounded the trumpets:

‘behalf even when I was convinced that the United was safely ahead of all comers in all branches of scienc - So after I recovered from my amazement that Oc day, I sat back to marvel at the sudden prestige that b: fell heir to; and to wonder at the spectacle of congres __ r AY discussing spaceflight learnedly, just as if they had be _ reading 2 a ae ever since they kissed their first b

_ For a while, it seemed to me that brains had grown s _ spectable that I thought I could detect congressmen t _ to speak grammatically, even though that meant losing

tl

_ All-American flavor of rough-hewn backwoods virtue.

_. Int those days everyone talked about revising our sy; of education, and introducing the revolutionary system of a

tually encouraging the brighter schoolboys and paying the some attention. _.~ But then, initial panic subsided. We sent up a numb _ satellites of our own and “Yankee know-how” was a p) 4to conjure with again. That left room for the thought _ after all, better schools cost money and who can affor

__throw money away by paying schoolteachers full-scale

eetorial-type salaries?

a _ What's

more,

:

something

else was

added.

a

Complac

and false economy are nothing over which to be shoc

_ for anyone who is surprised by the existence of either better turn in his sense of cynicism for a sharper-ed model.

_ The

pe_ Ty

"

“something

else” to which

I refer (and which

Shocking) is a definite counterattack against any changes’ i our basic educational philosophy and against the whole x _ tion of increasing emphasis on science on the part of son

_ of the eggheads themselves.

*

After all, there are eggheads and eggheads, in a variety Shee oe *Sea saa, err genera and species. We can make a broad classificatio

however, and divide them up into the humanists and the ‘SC

‘entists (which doesn’t mean, of course, that one man car

_ be a member of both groups).

. a

_

There is snobbery among the educated; there always h As long ago as the time of ancient Greece, the gre _ philosophers felt quite certain that to investigate amee _ deep and abstract thought was far superior to, and no than, investigation by experimentation. They felt that

spore been. ‘Se

light inthe beauty of the ordered 1

i

neti

.

universe out .

3

o

Battle of the Eggheads

©

197

grounded in a desire to apply the laws of the universe to the uses of everyday living. aa Perhaps this was because Greece was a society founded on — human slavery, so that there grew to be something disgraceful about manual labor. Experimentation, after all, was a — kind of manual labor and therefore fit only for slaves, really, 3 Applied science meant bending the glories of the universe to _ those things that should interest slaves. The very expression

‘liberal arts” comes

from the Latin

liberi meaning

_

“free —

men.” The liberal arts were suitable for free men; the me- — chanical and technical arts for slaves. A great thinker such as Archimedes,

who

couldn’t resist

working in applied science (and doing it superlatively well,

too); was nevertheless

ashamed of himself and would pub-—

lish only his theoretical work.

So experimental science had to wait two thousand years to 3 be born. :

_ And the attitude persists today, even among the experimental scientists themselves. The more theoretical a science, e higher it is in the scientists’ social scale. The descending

hierarchy

of science

is: mathematics,

astronomy,

physics,

chemistry, biology, and sociology. Within each discipline, there are subdivisions that can be similarly treated on the sis of theoretical content. Within chemistry, for instance, he descending hierarchy is: physical chemist, organic chem:biochemist, chemical engineer. j It is interesting that the various major disciplines of scisnce developed their modern contents in the order of their

d0sition in the hierarchy, as though it took longer and longer — or thinkers to break further and further from the Creek

ideal.

_ Modern sociology did not really come into its own until

E twentieth century (and perhaps hasn’t, even yet, really Zot-off the ground). Modern biology—including the cell the- —

ry, the germ theory of disease, and the theory of evolution y natural selection—is

a nineteenth-century

creation.

Mod- ..

am chemistry is the creature of Lavoisier and the eighteenth mtury; modern physics of Galileo and the seventeenth cen-

ury. Modern astronomy dates ixteenth century. _ _ Mathematics, finally, is so ks condescended to invent e, it never entirely died

back to Copernicus and the os Se highly theoretical that the it in the modern sense, Furin the centuries of darkness

fifteenth century, mathematics began to show ~

1s, eee

- But what lies beyond mathematics and the fifteenth tury? What most-high of modern life came into being the fourteenth century? Answer: the humanities.

Practitioners of all the sciences alike feel themselv (consciously or not) to be culturally inferior to those wh

+

specialize in the humanities. The humanists balance this situa

_ tion by feeling smugly superior to the scientists, and beca S in the very nature of the case, the humanists are extremely 7

“articulate, they have sold this attitude to the public generally

_ When any of us think of culture, we think of literature, art, music, philosophy, Latin, Greek—things like that. And in fact, so untouchable have “things like that” become, that beginning a discussion intended to be iconoclastic abot

them, I almost feel as though I were going to denoune _ mother love or refuse to salute the flag or something equal

_heinous.

_ Now what are the “humanities” anyway? Webster says _“The branches of polite learning regarded as primarily _ ducive to culture: especially the ancient classics and be

_ lettres; sometimes, secular, as distinguished from theologice _ Iearning.” __. The first part of the definition makes it seem obvioust _ the humanities are a type of “pure” learning not readily plied to the everyday problem of making a living. It is _ ideal study for leisure time and for those people who hay

_ leisure time.

_

And it is only human to fall into the fallacy that if @ in

plies b, then b must imply a. If the best examples of the ht _ manities have no practical application, then studies witho

_ practical application are good examples of the humanities; and, conversely, a study with a practical application is not a good example of the humanities; it is not a type of poli ~ learning, it is not conducive to culture. ____ Now the various sciences can’t avoid having practical us

_The sciences start with gentlemen

amateurs

but invariably

_ end with someone in a laboratory somewhere getting himsel

all dirty.

oe

_ Who would therefore argue that the immensely learn

gentleman with the vast world of the humanities at his f

rtips, but with no knowledge of science was not far n

an the

atory

worker wit

;ie

‘

:

ps

Battle of the Eseheuds

e. 199

of the sciences but unable to differentiate between a Picasso and a pizzicato.